Response to GH treatment in adult GH deficiency is predicted by gender, age, and IGF1 SDS but not by stimulated GH-peak.

OBJECTIVE: We studied whether the severity of GH deficiency (GHD) defined as i) GH-peak on stimulation tests (insulin tolerance test (ITT), arginine, and glucagon), ii) number of additional pituitary deficits, or iii) baseline IGF1 SDS could impact the response to GH treatment. We further explored whether iv) IGF1 SDS after 24 months of GH replacement or v) ΔIGF1 SDS from baseline to 24 months was related to the phenotypic response to GH treatment. DESIGN, PATIENTS, AND MEASUREMENTS: The patient cohort (n=1752; 50% women) was obtained from KIMS (Pfizer International Metabolic Database). The patients were divided into three groups of approximately equal size (tertiles) according to the stimulated GH-peak values and baseline IGF1 SDS and were studied at baseline, 12, and 24 months of GH therapy. RESULTS: Lower baseline IGF1 SDS predicted better response in weight, BMI, total cholesterol, and triglycerides, while IGF1 SDS after 24 months was associated with reduction in waist/hip ratio, total cholesterol, and improved quality of life (QoL). Age-correlated negatively with the response in body weight, BMI, waist, IGF1 SDS, and total and LDL-cholesterol. Response in weight and BMI was greater in men than in women, whereas women showed greater improvement in QoL than men. Patients with more severe GHD as assessed by lower GH-peaks and more pituitary hormone deficiencies had a greater increase in IGF1 SDS. The increase in IGF1 SDS was associated with a reduction in waist/hip ratio and an increase in weight, BMI, and triglycerides. There was no correlation with other lipids, blood pressure, or glucose. CONCLUSION: Our findings indicate that baseline and 24 months, IGF1 and its degree of increase during GH replacement were more important than stimulated peak GH to predict the phenotypic response.

Overall and cause-specific mortality in GH-deficient adults on GH replacement.

OBJECTIVE: Hypopituitarism is associated with an increased mortality rate but the reasons underlying this have not been fully elucidated. The purpose of this study was to evaluate mortality and associated factors within a large GH-replaced population of hypopituitary patients. DESIGN: In KIMS (Pfizer International Metabolic Database) 13,983 GH-deficient patients with 69,056 patient-years of follow-up were available. METHODS: This study analysed standardised mortality ratios (SMRs) by Poisson regression. IGF1 SDS was used as an indicator of adequacy of GH replacement. Statistical significance was set to P<0.05. RESULTS: All-cause mortality was 13% higher compared with normal population rates (SMR, 1.13; 95% confidence interval, 1.04-1.24). Significant associations were female gender, younger age at follow-up, underlying diagnosis of Cushing's disease, craniopharyngioma and aggressive tumour and presence of diabetes insipidus. After controlling for confounding factors, there were statistically significant negative associations between IGF1 SDS after 1, 2 and 3 years of GH replacement and SMR. For cause-specific mortality there was a negative association between 1-year IGF1 SDS and SMR for deaths from cardiovascular diseases (P=0.017) and malignancies (P=0.044). CONCLUSIONS: GH-replaced patients with hypopituitarism demonstrated a modest increase in mortality rate; this appears lower than that previously published in GH-deficient patients. Factors associated with increased mortality included female gender, younger attained age, aetiology and lower IGF1 SDS during therapy. These data indicate that GH replacement in hypopituitary adults with GH deficiency may be considered a safe treatment.

Similar clinical features among patients with severe adult growth hormone deficiency diagnosed with insulin tolerance test or arginine or glucagon stimulation tests.

OBJECTIVE: To determine whether insulin tolerance tests (ITTs), arginine stimulation tests (ASTs), and glucagon stimulation tests (GST) identify patients who have similar clinical features of growth hormone (GH) deficiency when a diagnostic GH threshold of 3 µg/L is used. METHODS: Data were obtained from the KIMS database (Pfizer International Metabolic Database). Comparisons were made between patients who underwent ITT, AST, or GST for GH peak, body mass index, lipids, waist circumference, waist-to-hip ratio, and quality of life. RESULTS: A total of 5453 tests were available from 4867 patients registered in the database (ITT = 3111, AST = 1390, GST = 952). Significant (P<.001) intraindividual correlations were observed between the GH peaks for ITT vs AST (r = 0.655), ITT vs GST (r = 0.445), and AST vs GST (r = 0.632). GH peaks in response to all tests were negatively correlated to the number of additional pituitary hormone deficiencies and positively correlated to the insulinlike growth factor 1 standard deviation score. Body mass index had a negative influence on all 3 tests. Most clinical variables did not differ between the groups when comparing GH-deficient patients according to the diagnostic test used. The only exceptions that showed any difference were body mass index (slightly higher in the AST and GST groups), triglyceride levels (increased in the GST group), and insulinlike growth factor 1 (standard deviation score) (lower in the ITT and AST groups than in the GST group). Waist circumference was greater and quality of life was worse in the GST group than in the other groups. CONCLUSIONS: The ITT, AST, and GST produce similar GH peaks, are influenced by similar clinical factors, and identify patients with similar features of GH deficiency at a diagnostic threshold of 3 µg/L.

Structured assessment of hypopituitarism after traumatic brain injury and aneurysmal subarachnoid hemorrhage in 1242 patients: the German interdisciplinary database.

Clinical studies have demonstrated that traumatic brain injury (TBI) and aneurysmal subarachnoid hemorrhage (SAH) are frequent causes of long-term disturbances of hypothalamo-pituitary function. This study aimed to assess the prevalence and associated factors of post-traumatic hypopituitarism in a large national registry of patients with TBI and SAH. Data were collected from 14 centers in Germany and Austria treating patients for TBI or SAH and performing endocrine assessments. Data were collected using a structured, internet-based study sheet, obtaining information on clinical, radiological, and hormonal parameters. A total of 1242 patients (825 TBI, age 43.5±19.7 years; 417 SAH, age 49.7±11.8 years) were included. We studied the prevalence of hypopituitarism reported based on different definitions of laboratory values and stimulation tests. Stimulation tests for the corticotropic and somatotropic axes were performed in 26% and 22% of the patients, respectively. The prevalence of hypopituitarism in the chronic phase (at least 5 months after the event) by laboratory values, physician diagnoses, and stimulation tests, was 35%, 36%, and 70%, respectively. Hypopituitarism was less common in the acute phase. According to the frequency of endocrine dysfunction, pituitary hormone secretion was impaired in the following sequence: ACTH, LH/FSH, GH, and TSH. TBI patients with abnormal stimulation tests had suffered from more severe TBI than patients with normal stimulation tests. In conclusion, our data confirm that hypopituitarism is a common complication of TBI and SAH. It is possible that patients with a higher likelihood of hypopituitarism were selected for endocrine stimulation tests.

Cardiovascular risk factors in patients with uncontrolled and long-term acromegaly: comparison with matched data from the general population and the effect of disease control.

CONTEXT: Data on cardiovascular risk in acromegaly are scanty and lack a clear correlation to epidemiological data. OBJECTIVE: Our aim was an evaluation of cardiovascular risk factors in patients with active acromegaly, a calculation of the Framingham risk score (FRS) compared with age- and gender-matched controls of the general population, and an evaluation of the effect of IGF-I normalization. DESIGN AND SETTING: We conducted a retrospective, comparative study at a university referral center. PATIENTS: A total of 133 patients with acromegaly (65 men, aged 45-74 yr) from the German Pegvisomant Observational Study were matched to 665 controls from the general population. MAIN OUTCOME MEASURES: Risk factors were measured at baseline and after 12 months of treatment with pegvisomant (n=62). RESULTS: Patients with acromegaly had increased prevalence of hypertension, mean systolic and diastolic blood pressure (BP), history of diabetes mellitus and glycosylated hemoglobin (all P<0.001) and decreased high-density lipoprotein, low-density lipoprotein, and total cholesterol (all P<0.001). FRS was significantly higher in patients with acromegaly compared with controls (P<0.001). At 12 months, systolic BP (P=0.04) and glycosylated hemoglobin (P=0.02) as well as FRS (P=0.005) decreased significantly. IGF-I was normalized in 62% (41 of 62). In these patients, glucose and systolic and diastolic BP was significantly lower than in partially controlled patients. SUMMARY: We found an increased prevalence of cardiovascular risk factors in acromegalic patients compared with controls. Control of acromegaly led to a significant decrease of FRS, implying a reduced risk for coronary heart disease. This was most significant in those patients who completely normalized their IGF-I levels. CONCLUSION: Disease control is important to reduce the likelihood for development of coronary heart disease.

Change of symptoms and perceived health in acromegalic patients on pegvisomant therapy: a retrospective cohort study within the German Pegvisomant Observational Study (GPOS).

OBJECTIVE: This study aimed at investigating how symptoms and perceived health changes in acromegalic patients during pegvisomant treatment in respect to IGF-1 levels and disease characteristics. DESIGN/PATIENTS: Retrospective, multicentre cohort study in 131 acromegalic patients within the German Pegvisomant Observational Study (GPOS). MEASUREMENTS: Outcome measure was the change of perceived health evaluated by the Patient-Assessed Acromegaly Symptom Questionnaire (PASQ) between baseline and after 1 year of pegvisomant therapy. Predictors were change in IGF-1 levels, maximal pegvisomant dosage, adverse events and comorbidities. RESULTS: Perspiration, soft tissue swelling and perceived health improved after 1 year of pegvisomant therapy while other symptoms such as headache, fatigue and joint pain remained largely unchanged over time. The highest mean IGF-1/upper limit of normal (ULN) values before pegvisomant therapy were found in those patients with a reported amelioration in perspiration and soft tissue swelling after 1 year of pegvisomant treatment. The highest mean decrease of IGF-1/ULN was found in those patients with reported amelioration of numbness and tingling of limbs. Other factors such as decrease in fasting glucose may play a role as independent predictor for some symptoms such as the improvement of headache, perspiration and perceived health, while other factors such as maximal pegvisomant dosage, occurrence of adverse events, tumour growth, or liver enzyme elevation did not play a predictive role. CONCLUSIONS: Patients' symptoms and perceived health are in part an independent construct, not merely reflecting IGF-1 status or biochemical control. Subjective measures should therefore be regularly documented in acromegalic patients as a patient-oriented indicator for treatment success.

Associations of age-dependent IGF-I SDS with cardiovascular diseases and risk conditions: cross-sectional study in 6773 primary care patients.

OBJECTIVE: We aimed at investigating the association of age-dependent IGF-I SDS with diabetes, dyslipidemia, hypertension, and heart diseases, in a large patient sample. BACKGROUND: IGF-I has been suggested to be associated with several diseases and a prognostic marker for the development of cardiovascular diseases and risk factors. The findings, though, have been inconsistent possibly due to the methodological factors. METHODS: We studied 6773 consecutive primary care patients, aged 18+ years, in a cross-sectional, epidemiological study in primary care, Diabetes Cardiovascular Risk-Evaluation: Targets and Essential Data for Commitment of Treatment study. All patients underwent a standardized clinical diagnostic and laboratory assessment. IGF-I levels were measured with an automated chemiluminescence assay system. We calculated the odds ratios (OR) for diseases in quintiles of IGF-I, and additionally analyzed the association of age-dependent IGF-I SDS with these conditions. RESULTS: After multiple adjustments for confounders, we found increased ORs for coronary artery disease in patients with high IGF-I. Women, but not men, with low IGF-I also showed increased ORs for coronary artery disease. Dyslipidemia was positively associated with IGF-I. Type 2 diabetes showed a curvilinear association with IGF-I SDS. CONCLUSIONS: The findings suggest the existence of multiple and complex interactions between IGF-I and several health conditions. The complex nature of disease- and subgroup-specific associations along with the methodological factors can be held responsible for divergent findings in previous studies.

Influence of GH substitution therapy in deficient adults on the recurrence rate of hormonally inactive pituitary adenomas: a case control study.

OBJECTIVE: Several studies documented metabolic and psychological benefits of GH substitution in deficient adults, most of them suffering from benign pituitary adenomas. Since GH substitution is considered to promote tumour regrowth, adequate treatment is performed with some reservation. Therefore, we aimed to elucidate the effect of GH replacement therapy on tumour recurrence following surgery. METHODS: In patients with hormonally inactive pituitary adenomas undergoing tumour surgery, a retrospective case-control study was performed. Pre- and postoperative magnetic resonance (MR) images of GH-treated and untreated patients were matched for best fit by two independent observers. The treated patients were retrieved from the surveillance programme of the German KIMS database and the untreated from the database of the Department of Neurosurgery, University of Erlangen. A total of 55 matched pairs were followed for at least 5 years. Tumour recurrence and progression rates were determined according to the postoperative MR. RESULTS: There were 16 tumour progressions in the treatment group and 12 in the control group. Statistical analysis revealed no significant increase in either recurrence (P = 0.317) or progression (P = 0.617) within the follow-up period of 5 years when GH was adequately replaced. CONCLUSIONS: This study provides further observational data of substitution therapy in GH-deficient adults with pituitary adenomas. Comparing long-term surgical results, we found no evidence that GH substitution should be withheld in deficient patients. Even residual tumour does not constitute a contraindication to GH replacement. However, since pituitary tumours are slow growing, an observational period of 5 years may not have been long enough to verify any absolute influence on recurrence potential.

Clinical implications of residual growth hormone (GH) response to provocative testing in adults with severe GH deficiency.

CONTEXT: The diagnosis of GH deficiency (GHD) in adults is based on provocative tests of GH release, all influenced by clinical factors. It is unknown whether the amount of residual GH reserve under the cutoff value has any physiological implication. OBJECTIVES: We used a large pharmacoepidemiological database of adult GHD (KIMS) and tested the impact of confounding factors on GH release of no greater than 3 microg/liter after an insulin tolerance test (ITT) and evaluated its potential physiological role. DESIGN, SETTINGS, AND PATIENTS: A total of 1098 patients fulfilled the criteria of having a GH peak of no greater than 3 microg/liter during ITT as well as documented IGF-I levels. OUTCOMES: The impact of underlying hypothalamic-pituitary disease, age, gender, body weight, as well as treatment modalities such as irradiation on peak GH level to ITT was evaluated, and the correlations between GH peak and targets of GH action were analyzed. RESULTS: The GH response to ITT was regulated by gender, age, and the number of additional pituitary deficiencies. In a multivariate evaluation, the extent of hypothalamic-pituitary dysfunction was the most important single predictor of GH peak in ITT. GH peaks in ITT were positively related to IGF-I levels and high-density lipoprotein-cholesterol, as well as inversely to triglycerides. CONCLUSIONS: Even in adult severe GHD, GH release appears to be regulated by factors defined to play an important role in normal GH secretion. The impact of very low GH release on IGF-I and lipid parameters indicates a persistent physiological role of low GH concentrations in severely affected patients with GHD.

Quality of life and psychiatric sequelae following aneurysmal subarachnoid haemorrhage: does neuroendocrine dysfunction play a role?

OBJECTIVE: Patients who have sustained aneurysmal subarachnoid haemorrhage (SAH) often suffer persistent impairments in their quality of life (QoL) and psychological disturbances despite a good neurological outcome. In the light of the high prevalence of partial hypopituitarism in SAH survivors demonstrated in recent investigations, we aimed to determine whether neuroendocrine dysfunction has an impact on QoL and neurobehavioural symptoms in these patients. DESIGN/PATIENTS: QoL, depression and psychological distress were assessed in 40 SAH survivors who had undergone endocrine function testing at least 1 year after the haemorrhage. MEASUREMENTS: QoL was assessed using the Nottingham Health Profile (NHP), the Quality of Life Assessment of Growth Hormone Deficiency in Adults (QoL-AGHDA) and the Short Form-36 questionnaire (SF-36). The Beck Depression Inventory (BDI) and the Impact of Event Scale (IES) were used to evaluate depression and symptoms of current subjective distress in response to the SAH as a stressful life event, respectively. RESULTS: In a stepwise multiple regression analysis, basal cortisol level was included as the first and often only predictor for several QoL domains assessing psychological aspects of well-being and depression whereas physical aspects of QoL were predicted primarily by neurological recovery from the SAH. Severe GH deficiency (GHD) was the first predictor for the criterion NHP subscale 'Energy' and highest stimulated ACTH level in the insulin tolerance test (ITT) was the first predictor for disturbed sleep as assessed with the NHP subscale 'Sleep'. CONCLUSION: Our results provide preliminary data that neuroendocrine disturbances contribute to disturbed QoL, depression and sleeping disturbances in SAH patients.

Experience from the German pegvisomant observational study.

BACKGROUND: The German Pegvisomant Observational Study (GPOS) was created immediately after marketing authorisation was received in Germany for Somavert (pegvisomant) for the treatment of patients with acromegaly. In August 2006, the database underwent its fifth interim analysis of 263 patients, the vast majority of whom previously had insufficient disease control with other treatment modalities. The GPOS documents both safety and efficacy aspects of the treatment of patients with acromegaly by the first growth hormone-receptor antagonist, pegvisomant. This treatment led to normalization of disease activity in most patients, had favourable effects on glucose metabolism and improved signs and symptoms of the disorder. The safety profile indicates that pegvisomant treatment is well tolerated, and tumour growth is noted to occur at the same rate as for somatostatin analogue treatment. Transaminase elevations occurred in 16 of the 263 patients but spontaneously resolved in eight of them and promptly normalised in five patients who discontinued treatment. GPOS is presently the largest database of pegvisomant-treated patients, and it comprises more than 87% of all patients treated with pegvisomant in Germany. CONCLUSIONS: The GPOS database provides important information about treatment modalities, safety and efficacy of pegvisomant in patients with acromegaly.

Healthcare utilization, quality of life and patient-reported outcomes during two years of GH replacement therapy in GH-deficient adults--comparison between Sweden, The Netherlands and Germany.

OBJECTIVE: This study set out to determine the change in quality of life (QoL) and healthcare utilization during 2 years of growth hormone (GH) replacement therapy in adults with GH deficiency. Data were compared from three European countries. DESIGN: Analysis was made from KIMS, the Pfizer International Metabolic Database on adult GH deficiency. METHODS: QoL and healthcare utilization were measured at baseline and after 1 and 2 years of GH replacement in patient cohorts from Sweden (n = 302), The Netherlands (n = 103) and Germany (n = 98). QoL was assessed by the QoL-Assessment in Growth Hormone Deficient Adults (QoL-AGHDA) questionnaire, and the KIMS Patient Life Situation Form was used to evaluate healthcare utilization. RESULTS: QoL improved significantly (P < 0.0001) and comparably in all three cohorts. The improvement was seen during the first year of treatment and QoL remained improved during the second year. The number of days in hospital was reduced by 83% (P < 0.0001) during GH replacement. There were no country-specific differences either at baseline or during follow-up. The same was true for the number of days of sick leave (reduction of 63%; P = 0.0004). Significant reductions were recorded in the number of doctor visits in each of the three cohorts after 2 years of GH replacement (P < 0.05). CONCLUSIONS: This study provides a detailed comparative analysis of GH replacement therapy in GHD patients in three European countries. Despite some differences in treatment strategies, the beneficial effects on QoL, patient-reported outcomes and healthcare utilization are essentially similar in the healthcare environment of Western European countries.

Opposite associations of age-dependent insulin-like growth factor-I standard deviation scores with nutritional state in normal weight and obese subjects.

OBJECTIVE: Insulin-like growth factor-I (IGF-I) has been suggested to be a prognostic marker for the development of cancer and, more recently, cardiovascular disease. These diseases are closely linked to obesity, but reports of the association of IGF-I with measures of obesity are divergent. In this study, we assessed the association of age-dependent IGF-I standard deviation scores with body mass index (BMI) and intra-abdominal fat accumulation in a large population. DESIGN: A cross-sectional, epidemiological study. METHODS: IGF-I levels were measured with an automated chemiluminescence assay system in 6282 patients from the DETECT study. Weight, height, and waist and hip circumference were measured according to the written instructions. Standard deviation scores (SDS), correcting IGF-I levels for age, were calculated and were used for further analyses. RESULTS: An inverse U-shaped association of IGF-I SDS with BMI, waist circumference, and the ratio of waist circumference to height was found. BMI was positively associated with IGF-I SDS in normal weight subjects, and negatively associated in obese subjects. The highest mean IGF-I SDS were seen at a BMI of 22.5-25 kg/m2 in men (+0.08), and at a BMI of 27.5-30 kg/m2 in women (+0.21). Multiple linear regression models, controlling for different diseases, medications and risk conditions, revealed a significant negative association of BMI with IGF-I SDS. BMI contributed most to the additional explained variance to the other health conditions. CONCLUSIONS: IGF-I standard deviation scores are decreased in obesity and underweight subjects. These interactions should be taken into account when analyzing the association of IGF-I with diseases and risk conditions.

Prevalence of pituitary deficiency in patients after aneurysmal subarachnoid hemorrhage.

After aneurysmal subarachnoid hemorrhage (SAH), patients frequently present with persistent bodily, psychosocial, and cognitive impairments that resemble those of patients with untreated partial or complete pituitary insufficiency. Because of these similarities, the authors hypothesized that aneurysmal SAH may cause pituitary dysfunction. Pituitary function testing was performed in 40 aneurysmal SAH patients between 12 and 72 months after the SAH. A combined TRH-LHRH-arginine test and the insulin tolerance test were performed on two separate days. Only 18 of 40 (45%) of the tested patients had normal pituitary function. Five of 40 exhibited isolated severe GH deficiency (GHD), and an additional three of 40 had severe GHD plus corticotroph deficiency. Isolated corticotroph deficiency was seen in 13 of 40 patients, and one patient showed isolated thyrotroph deficiency. All but one patient with corticotroph insufficiency were female. Patients with severe GHD had gained significantly more weight since their SAH than patients without GHD and exhibited a significantly higher body mass index. None of the clinical parameters indicative of a poor neurological outcome in aneurysmal SAH were related to pituitary insufficiency. In summary, neuroendocrine dysfunction was identified in a substantial portion of patients with previous aneurysmal SAH and should be borne in mind as a potential long-term sequel of the illness.

Autoantibodies to thyroperoxidase (TPOAb) in a large population of euthyroid subjects: implications for the definition of TPOAb reference intervals.

OBJECTIVE: Measurement of autoantibodies against thyroperoxidase (TPOAb) plays an important role in the diagnosis of autoimmune thyroid disease. The assessment of reference intervals for TPOAb, however, is a controversial issue since elevated TPOAb values are sometimes found in subjects without other evidence of thyroid disease. METHODS: TPOAb were measured in 1,295 euthyroid individuals using a highly sensitive, fully automated chemiluminescence assay (Advantage A-TPO, Nichols Institute Diagnostics, CA, USA). The study subjects participated in a population study on the prevalence of thyroid disorders in the German federal state of Saxony, an area of mild iodine deficiency. RESULTS: TPOAb above the detection limit of 0.45 IU/ml were found in 1,277/1,295 euthyroid individuals. TPOAb values in the low measurable range below 1.1 IU/ml followed a normal distribution, and this was independent of age and sex. When using a cut-off value of 1.1 IU/ml, which corresponds to a sensitivity of 79% and a specificity of 95% resulting from the receiver-operator characteristic plot for discrimination between a main type and other types with a higher mean value of TPOAb, elevated TPOAb were found in 14.4% of euthyroid men and in 25.8% of euthyroid women. CONCLUSIONS: The results demonstrate for the first time that TPOAb are detectable in nearly all euthyroid individuals and that TPOAb values in the low measurable range are normally distributed. The distribution of TPOAb values in the low range is independent of age and sex. Based on these data, reference intervals for TPOAb can be defined that are independent of the population investigated. The clinical significance of slightly elevated TPOAb, however, has still to be defined by prospective studies.

Serum insulin-like growth factor I reference values for an automated chemiluminescence immunoassay system: results from a multicenter study.

BACKGROUND: Analysis of insulin-like growth factor I in serum (S-IGF-I) is an integral component in the diagnosis of GH-related disorders and is going to be of interest in the diagnosis and follow-up of many disorders. The objective of the present study was to develop cross-sectional reference values for S-IGF-I measured by an automated chemiluminescence immunoassay (Nichols Advantage). METHODS: The study included samples from 3,961 healthy subjects (2,201 males, 1,760 females) aged 1 month to 88 years. Six laboratories were involved in this study and the samples were analyzed by one of seven automated immunoassay systems run in these laboratories. For data analysis, polynomial age and sex-specific models were fitted after transformation of S-IGF-I values. RESULTS: The results show the well-known age dependency of S-IGF-I levels. At ages <20, higher S-IGF-I levels were seen in girls with an estimated mean peak of 410 microg/l at age 14 and an estimated mean peak of 382 microg/l at age 16 in boys. Thereafter, a rapid decrease was seen to approximately 25 years of age, followed by a slow age-dependent decrease. In adulthood, S-IGF-I in males were slightly, but significantly higher than in females. It could be shown that the mean values of some reference sample subgroups differed significantly from the total mean. However, the multicenter approach used in this study reduces the impact of systematic population, sample handling and laboratory differences on the calculated reference mean. CONCLUSION: The present study establishes age- and sex-specific reference values for a fully automated immunoassay system based on a large population of healthy subjects. The established reference values may be used for this immunoassay system in different laboratories provided that the systematic difference between systems is low.

Impact of estrogen replacement therapy in a male with congenital aromatase deficiency caused by a novel mutation in the CYP19 gene.

Recent reports of the impact of estrogen receptor alpha and aromatase deficiency have shed new light on the importance of estrogen for bone formation in man. We describe a novel mutation of the CYP19 gene in a 27-yr-old homozygous male of consanguinous parents. A C to A substitution in intron V, at position -3 of the splicing acceptor site before exon VI of the CYP19 gene, is the likely cause of loss of aromatase activity. The mRNA of the patient leads to a frameshift and a premature stop codon 8 nucleotides downstream the end of exon V. Both parents were shown to be heterozygous for the same mutation. Apart from genua valga, kyphoscoliosis, and pectus carniatus, the physical examination was normal including secondary male characteristics with normal testicular size. To substitute for the deficiency, the patient was treated with 50 micro g transdermal estradiol twice weekly for 3 months, followed by 25 micro g twice weekly. After 6 months estrogen levels (<20 at baseline and 45 pg/ml at 6 months; normal range, 10-50) and estrone levels (17 and 34 ng/ml; normal range, 30-85) had normalized. Bone maturation progressed and the initially unfused carpal and phalangeal epiphyses began to close within 3 months and were almost completely closed after 6 months. The bone age, assessed by roentgenographic standards for bone development by Gruelich and Pyle, was 16.5 at baseline and 18-18.5 yr after 6 months of treatment. Bone density of the distal radius (left), assessed by quantitative computed tomography, increased from 52 to 83 mg/cm(3) (normal range, 120-160) and bone mineral density of the lumbar spine, assessed by dual-energy x-ray-absorptiometry, increased from 0.971 to 1.043 g/cm(2) (normal range, >1.150). Osteocalcin as a bone formation parameter increased from 13 to 52 micro g/l (normal range, 24-70) and aminoterminal collagen type I telopeptide as a bone resorption parameter increased from 62.9 to 92.4 nmol/mmol creatinine (normal range, 5-54). Semen analysis revealed oligoazoospermia (17.4 million/ml; normal >20) at baseline. After 3 months of treatment, the sperm count increased (23.1 million/ml) and decreased rapidly (1.1 million/ml) during the following 3 months. The sperm motility was reduced at baseline and decreased further during treatment. Area under the curve of insulin, C-peptide, and blood glucose levels during oral glucose tolerance test decreased after 6 months (insulin: 277 vs. 139 micro U/ml.h; C-peptide 52 vs. 15 ng/m.h; area under the curve glucose: 17316 vs. 12780 mg/d.min). Triglycerides (268 vs. 261 mmol/liter) and total cholesterol levels (176 vs. 198 mmol/liter) did not change significantly, but the low-density lipoprotein/high-density lipoprotein ratio decreased from 5.37 to 3.56 and lipoprotein (a) increased from 19.9 to 60.0 mg/dl (normal range, <30). In this rare incidence of estrogen deficiency, estrogen replacement demonstrated its importance for bone mineralization and maturation and glucose metabolism in a male carrying a novel mutation in the CYP19 gene.

Sensitive calcitonin measurement by two-site immunometric assays: implications for calcitonin screening in nodular thyroid disease.

The aim of this study was to investigate the impact of analytical aspects on the clinical usefulness of calcitonin (CT) measurement. In a retrospective analysis, CT levels measured by a polyclonal immunometric assay (Scantibodies Laboratory, CA, USA) were evaluated in various clinical situations. CT in newly diagnosed medullary thyroid cancer (MTC) (n = 20) ranged from 15.5-87130 pg/ml (median 661 pg/ml). Levels >10 pg/ml were seen in 7.3% of 314 patients with benign nodules, 48.9% of 45 patients with impaired kidney function, 97.7% of 87 patients on hemodialysis, 30.2% of 43 patients after renal transplantation, and in 71.0% of 31 patients with critical illnesses. Subgroups of patients were reevaluated by two monoclonal immunometric assays specific for mature CT. CT levels measured by the monoclonal immunometric assays were highly correlated to the polyclonal assay results in MTC patients, but were significantly different with a lower incidence of elevated levels in patients with renal disease and critical illnesses. In conclusion, highly sensitive assays with cut-off values of 10 pg/ml or below are mandatory for CT screening in nodular thyroid disease. The specificity of CT measurement in patients with renal disease and critical illnesses is higher with monoclonal assays specific for monomeric CT. These methodological aspects have to be regarded if CT measurement is used for decision making in nodular thyroid disease.

Characterization of T(4)-binding globulin cleaved by human leukocyte elastase.

T(4)-binding globulin (TBG) serves to maintain an important serum pool of thyroid hormones and to prevent their excessive loss in urine. TBG has also been implicated in the tissue distribution and targeted delivery of the hormones, the mechanisms of which remain unclear. By virtue of sequence homology, TBG belongs to the serine proteinase inhibitors superfamily of proteins that are characterized by a reactive site loop serving as a recognition site for serine proteinases. However, both TBG and another serpin with hormone transport function, corticosteroid-binding globulin, are noninhibitory. Cleavage of corticosteroid-binding globulin by human leukocyte elastase results in the reduction of its hormone-binding affinity and capacity. In this communication we confirm previous observations that TBG is also cleaved by elastase and undergoes the characteristic conformational changes. In addition, contrary to a previous report, the present work demonstrates that the cleaved product has reduced T(4)-binding affinity and, as expected, increased heat stability. Additional fragmentation of the molecule results in the loss of the hormone-binding site that is in agreement with a recent in vivo observation of apparent consumption at sites of inflammation. These data suggest that TBG may play a role in the targeted delivery of thyroid hormones to tissues rich in proteinases.

Characterization and primary structures of bovine and porcine thyroxine-binding globulin.

Thyroxine-binding globulin (TBG) is the major serum transport protein for iodothyronines in most of the large, omni- or herbivorous mammals. Characterization of human TBG (hTBG), including its 20 known natural variants, allowed the identification of the ligand-binding site and a correlation of diminished synthesis or loss of function with mutations in the TBG gene. Further refinement of the structure-function correlation, especially the high binding affinity and heat stability, requires characterization of other mammalian TBGs, of which only rat and sheep TBG were available. We now present some of the chemical and physical properties of bovine TBG (bTBG) and porcine TBG (pTBG) and their primary structures deduced from their cDNA sequences. The serum concentrations of bTBG and pTBG estimated by Scatchard analysis of T(4)-binding were similar to hTBG. The T(4)-binding affinity of human, bovine and porcine TBGs were all similar, at 1.2x10(10) M(-1). However, heat stability of the animal TBGs was reduced, with a half life of denaturation of 7 min (bTBG) and 5 min (pTBG) at 55 degreeC, compared with 21 min for hTBG. Nucleotide alignment revealed identity with hTBG of 85.5% (bTBG) and 83.7% (pTBG) and amino acid identity of 82.8% (bTBG) and 82.6% (pTBG). As expected, the relevant parts of the ligand-binding domain (amino acids 215-291, and 363-395) were highly conserved at more than 95% similarity. Comparison of the five known mammalian TBGs allows focusing of future mutagenesis experiments to further characterize the properties of the molecule.