Acute effects of etidronate on glucocorticoid-induced bone degradation.

OBJECTIVES: To study the acute short-term effects on the biochemical parameters of calcium and bone homeostasis in post-menopausal women treated with a high dose of prednisone alone or with additional etidronate, before and during 5 days of treatment. METHODS: Serum calcium, phosphorus, creatinine, alkaline phosphatase activity, osteocalcin, carboxy-terminal propeptide of type I procollagen (PICP), cross-linked carboxy-terminal telopeptide of type I collagen (ICTP), parathyroid hormone (PTH), 25-hydroxyvitamin D and urinary excretion of calcium over 24 h were measured before and during 5 days of treatment in 14 post-menopausal women treated with a high dose of prednisone (60 mg/day) alone (group A) or combined with cyclical etidronate (group B). RESULTS: Significant differences from baseline were found in osteocalcin and urinary excretion of calcium in both groups and for ICTP in group B. Significant differences between groups were calculated at day 5 of the study for osteocalcin, ICTP and 24 h urine calcium excretion (P < 0.01). Urinary excretion of calcium over 24 h increased in group A (+14.7%; P < 0.05) and decreased in group B (-22.1%; P < 0.01). Osteocalcin levels decreased in group A (- 38.1%) and increased in group B (+27.4%; both P < 0.01). ICTP decreased only in group B (-19.4%; P < 0.01). CONCLUSIONS: The results are consistent with the fact that etidronate is acutely able to prevent bone resorption due to corticosteroids. The increase in osteocalcin in the etidronate-treated group is a new feature. A direct or indirect (PTH, 1,25 vitamin D?) stimulatory effect of etidronate on the osteoblast cannot be excluded.

Diminished effect of etidronate in vitamin D deficient osteopenic postmenopausal women.

OBJECTIVE: The effects of vitamin D deficiency in osteopenic postmenopausal women treated with intermittent cyclical etidronate have been studied. Bone mass and biochemical parameters as bone markers were measured before and after one year of therapy with intermittent cyclical etidronate. RESULTS: In 30 patients without vitamin D deficiency, bone mass in the lumbal spine and femoral neck was significantly increased compared to 28 vitamin D deficient patients. After cyclical intermittent etidronate therapy, serum osteocalcin and PTH were significantly increased in the vitamin D deficient patients, whereas in non-vitamin D deficient patients they did not change. CONCLUSION: It is worthwhile measuring serum vitamin D before starting etidronate therapy and, in case of deficiency, to give vitamin D.

An improved method for the determination of islet amyloid polypeptide levels in plasma.

We describe an improved method for the determination of islet amyloid polypeptide (IAPP) levels in plasma. Plasma is first extracted with acid-acetone, followed by a specific and sensitive radioimmunoassay (RIA) for IAPP using rabbit-anti-human-IAPP serum. Recovery of synthetic IAPP from plasma was 82 +/- 6% (n = 16). Standard samples, prepared in 'hormone-free' serum, were also extracted with acid-acetone. Displacement curves of serially diluted acid-acetone extracted plasma samples were parallel to the standard curve. The lower detection limit of the RIA was 2.3 +/- 0.1 fmol/sample (n = 5). Intra-assay variations for IAPP concentrations of 4, 17 and 32 pM were 16.3% (n = 10), 9.2% (n = 10) and 6.2% (n = 10); interassay variations were 35.9% (n = 14), 19.9% (n = 15) and 15.4% (n = 15), respectively. Non-stimulated IAPP levels ranged from 2.4 to 12 pM (mean 6 +/- 4 pM, n = 10) in healthy control subjects. IAPP was not detectable in type 1 (insulin-dependent) diabetic patients before and after glucagon administration. In type 2 (non-insulin-dependent) diabetic patients basal levels ranged from 2.2 to 14.5 pM and glucagon-stimulated levels ranged from 2.2 to 38.9 pM. The increase in IAPP varied from 0 to 24.4 pM. The anti-human-IAPP serum had full cross-reactivity with rat IAPP (= mouse IAPP). Transgenic mice overexpressing the human IAPP gene showed elevated plasma IAPP levels as compared to (non-transgenic) control mice. It is concluded that the method presented for the determination of IAPP in plasma is reliable and easy to perform, yielding reproducible results.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone histomorphometry and serum concentrations of intact parathyroid hormone (PTH(1-84)) in patients with primary hyperparathyroidism.

The consequences of bone disease in primary hyperparathyroidism (PHPT) are still a matter of discussion. We studied transiliac bone biopsies of 24 patients (9 men and 15 women) with mild to moderate PHPT, proven by surgery. Histomorphometric data were compared with control values obtained from autopsy bone samples. The biopsies of the PHPT patients were characterized by increased trabecular bone volume (P < 0.01) and surface (P < 0.02), increased osteoid volume and increased osteoid and resorption surfaces (P < 0.001). Cortical porosity showed a non-significant increase in the PHPT patients. In the patients the fasting serum concentrations of parathyroid hormone (PTH(1-84)) correlated positively with cortical porosity (r = 0.50, P = 0.02), osteoid volume (r = 0.40, P = 0.05), osteoid surface (r = 0.50, P = 0.01), and eroded surface (r = 0.59, P < 0.01). It is concluded that moderate PHPT is associated with preservation of trabecular bone, whereas cortical bone may be lost in these patients. Cortical porosity and the parameters of bone turnover correlate well with the fasting serum PTH(1-84) concentration.

Chronic overproduction of islet amyloid polypeptide/amylin in transgenic mice: lysosomal localization of human islet amyloid polypeptide and lack of marked hyperglycaemia or hyperinsulinaemia.

Type 2 (non-insulin-dependent) diabetes mellitus is characterised by hyperglycaemia, peripheral insulin resistance, impaired insulin secretion and pancreatic islet amyloid formation. The major constituent of islet amyloid is islet amyloid polypeptide (amylin). Islet amyloid polypeptide is synthesized by islet beta cells and co-secreted with insulin. The ability of islet amyloid polypeptide to form amyloid fibrils is related to its species-specific amino acid sequence. Islet amyloid associated with diabetes is only found in man, monkeys, cats and racoons. Pharmacological doses of islet amyloid polypeptide have been shown to inhibit insulin secretion as well as insulin action on peripheral tissues (insulin resistance). To examine the role of islet amyloid polypeptide in the pathogenesis of Type 2 diabetes, we have generated transgenic mice with the gene encoding either human islet amyloid polypeptide (which can form amyloid) or rat islet amyloid polypeptide, under control of an insulin promoter. Transgenic islet amyloid polypeptide mRNA was detected in the pancreas in all transgenic mice. Plasma islet amyloid polypeptide levels were significantly elevated (up to 15-fold) in three out of five transgenic lines, but elevated glucose levels, hyperinsulinaemia and obesity were not observed. This suggests that insulin resistance is not induced by chronic hypersecretion of islet amyloid polypeptide. Islet amyloid polypeptide immunoreactivity was localized to beta-cell secretory granules in all mice. Islet amyloid polypeptide immunoreactivity in beta-cell lysosomes was seen only in mice with the human islet amyloid polypeptide gene, as in human beta cells, and might represent an initial step in intracellular formation of amyloid fibrils.(ABSTRACT TRUNCATED AT 250 WORDS)

Normocalcaemic hyperparathyroidism after parathyroidectomy: a retrospective study.

Forty-eight patients with proven hyperparathyroidism underwent parathyroidectomy. All patients were post-operatively normocalcaemic and free of symptoms due to their pre-operative hypercalcaemic state. However, 20 (42%) post-operative patients still had increased serum PTH and low serum phosphate levels.

Plasma concentrations of islet amyloid polypeptide after glucagon administration in type 2 diabetic patients and non-diabetic subjects.

Islet amyloid polypeptide (IAPP) is the main constituent of pancreatic islet amyloid, observed in the pancreases from patients with Type 2 diabetes mellitus. IAPP is synthesized by the pancreatic beta-cells. In order to study the secretion characteristics of IAPP in Type 2 diabetes mellitus, plasma IAPP was measured during a provocation test with glucagon in 33 Type 2 diabetic patients and 18 non-diabetic subjects. The median fasting IAPP level was 5.7 (range 1.1-13.1) pmol l-1 in the 27 patients treated with oral hypoglycaemic agents and 2.7 (1.9-5.9) in the 6 patients on insulin. In the non-diabetic group fasting IAPP was 5.7 (2.2-10.1). Six minutes after glucagon administration median IAPP rose to 9.4 (1.7-31.0) and 6.1 (5.1-10.2) in the respective diabetic groups, and to 16.8 (4.0-41.0) in the non-diabetic subjects (p << 0.05). The correlation coefficient between change in IAPP and change in C-peptide was 0.68 in the diabetic group. We conclude that intravenous administration of glucagon stimulates IAPP release from the beta-cell. This provocation test is easy to perform and can be used on a large scale in the study of IAPP secretion in Type 2 diabetes mellitus.

Calcitonin gene-related peptide, the menstrual cycle and premenstrual syndrome.

Calcitonin gene-related peptide plasma levels were measured during four different phases of ovulatory menstrual cycles, in eight women suffering from the premenstrual syndrome and in eight controls. No significant fluctuations in calcitonin gene-related peptide levels occurred during the menstrual cycle. Neither were there significant differences in calcitonin gene-related peptide levels between the premenstrual syndrome and control groups.

Urinary albumin excretion, cardiovascular disease, and endothelial dysfunction in non-insulin-dependent diabetes mellitus.

Raised urinary albumin excretion (UAE) is associated with an increased risk of cardiovascular disease in non-insulin-dependent diabetes mellitus (NIDDM). We have examined the role of endothelial dysfunction as a possible explanation for this association in 94 NIDDM patients by investigating UAE, new cardiovascular events, and plasma concentration of von Willebrand factor (vWF), an indicator of endothelial dysfunction. At baseline, 66 patients had normal UAE (less than 15 micrograms/min), which remained normal in 33 (group 1) and increased in 33 (to median 31.5 micrograms/min, group 2). In 28 patients, baseline UAE was abnormal (67.1 micrograms/min, group 3). Follow-up ranged between 9 and 53 months. vWF did not change in group 1 (median 128% at baseline and 123% at follow-up), but increased in group 2 (from 116 to 219%, p less than 0.0001) and group 3 (from 157 to 207%, p = 0.0005). Baseline level of and change in vWF were strongly related to the development of microalbuminuria (R2 = 0.60, p less than 0.0001), but cardiovascular risk factors were not (R2 = 0.14). Raised baseline UAE was associated with an increased risk of new cardiovascular events only in patients with vWF concentrations above the median (relative risk 3.66, 95% CI 1.3-11.9) and not in patients with lower vWF (0.19, 0.01-1.33). In addition, the cardiovascular risk associated with increased UAE was modified by low compared with high concentrations of serum high density lipoprotein cholesterol (2.86 [1.03-8.48] vs 0.15 [0.01-1.43]). Dysfunction of vascular endothelium may be a link between albuminuria and atherosclerotic cardiovascular disease in NIDDM.

Normocalcemia with persistent increase of parathyroid hormone: a prospective study.

Twelve patients were followed up for 3 months after parathyroidectomy. Serial measurements of serum parathyroid hormone (PTH), calcium, and phosphate were made. Four patients had an increased serum PTH postoperatively, which was already apparent by the third postoperative day. All patients became normocalcemic. Their hyperparathyroid-like phosphate parameters indicated that we were dealing with a biologically active PTH. Using preoperative biochemical parameters it was impossible to predict which patients would have an increased PTH postparathyroidectomy (PTX). Probably the patients with high PTH post-PTX had higher parathyroid volumes. In our opinion after PTX, a normocalcemic high PTH situation should be avoided by 3 1/2 parathyroid gland extirpation in all cases.

Efficacy of low-dose captopril in addition to furosemide and spironolactone in patients with decompensated liver disease during blunted diuresis.

The renin-angiotensin-aldosterone system is activated by diuretics and involved in the diuretic resistance of cirrhotic patients with ascites and oedema. In previous studies relatively high doses of captopril (25-400 mg daily) were unsuccessful in promoting diuresis and natriuresis in these patients. We analyzed the efficacy of a low dose of captopril in eight patients with massive ascites resistant to therapy of salt/fluid restriction and increasing doses of spironolactone and furosemide. Mean duration of diuretic use was 73 days (range 7-240 days). After at least 3 days of observation on 80 mg furosemide and 100 mg spironolactone only, captopril was added. Four out of eight patients responded with an increase in natriuresis and diuresis; daily dose of captopril was 20.6 mg in responders and 26.5 mg in non-responders. After the addition of captopril the mean weight change was -7.5 kg in responders and +0.25 kg in non-responders. Mean urinary sodium output in responders increased from 72.8 (S.D. = 35.2) to 128.5 (63.5) mmol within 10 days. Increased diuresis in responders made diuretic reduction necessary: mean furosemide from 80 to 53.3 mg, and mean spironolactone from 100 to 68.1 mg. Creatinine clearances remained stable. High levels of plasma renin activity, plasma aldosterone and angiotensin-II were found in all patients. Non-responders showed more severe hyponatremia and higher vasopressin levels. Natriuretic atrial factor (NAF) was in the upper-normal range or slightly elevated in both groups. In non-responders we noticed low levels of cGMP in 24-h urine, compared with responders.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term follow-up in four large MEN 2 families in The Netherlands.

Results of follow-up studies in four large multiple endocrine neoplasia type 2A families (total of 95 patients affected) have shown a positive effect on the course of the disease since early screening and intervention were initiated in 1974.

Calcium supplementation reduces vertebral bone loss in perimenopausal women: a controlled trial in 248 women between 46 and 55 years of age.

To study the effect of calcium supplementation on perimenopausal bone loss, 295 women were randomized into a control group and 2 supplementation groups receiving, respectively, 1000 and 2000 mg elemental calcium/day for a period of 2 yr. We observed a significant decrease in lumbar bone loss in relation to the calcium supplementation (mean loss after 2 yr of 3.5% in the control group vs. 1.3% and 0.7% in the 1000 and 2000 mg groups, respectively), a significant increase in urinary calcium excretion, and a significant decrease in the urinary hydroxyproline/creatine ratio, serum alkaline phosphatase, osteocalcin, and 1,25-dihydroxyvitamin D. The effect of calcium supplementation on lumbar bone loss was significant in the first year of supplementation, but not in the second. However, the urinary hydroxyproline/creatinine ratio and the serum alkaline phosphatase level remained significantly decreased in the treatment groups at the end of the study; this was not the case for serum osteocalcin. Calcium supplementation did not have a significant effect on metacarpal cortical bone loss. The difference in biochemical parameters between the 2 supplementation groups was small. No significant interaction was observed between the menopausal status of the subjects and the effect of calcium supplementation. We conclude that calcium supplementation retards lumbar bone loss in the first year of calcium supplementation by reducing bone turnover. However, the effect on lumbar bone loss over a longer time span is still uncertain.

von Willebrand factor and development of diabetic nephropathy in IDDM.

We tested the hypothesis that dysfunction of vascular endothelium, indicated by an increase in plasma level of von Willebrand factor (vWF), is present in patients with insulin-dependent diabetes mellitus (IDDM) who develop diabetic nephropathy (DN). DN was classified as absent (urinary albumin excretion [UAE] rate less than 15 microgram/min), incipient (UAE rate 15-200 micrograms/min), or clinical (UAE rate greater than 200 micrograms/min). We followed a cohort of 59 patients for a median of 3 yr. At baseline, 52 patients had no DN, 6 had incipient DN, and 1 had clinical DN. At follow-up, 38 patients had no DN (group 1). Incipient DN had developed in 14 patients and worsened in 3 patients. Clinical DN had worsened in 1 patient. Together, these 18 patients comprised group 2. A decrease in UAE was observed in the remaining three patients with incipient DN at baseline (group 3). In group 1, vWF--measured by immunoelectrophoresis and expressed as a percentage of normal--increased slightly (median 10%, range -43 to 145, P = 0.009). In group 2, vWF increased in all patients (median 80%, range 14 to 206 [corrected], P = 0.0002 vs. baseline and group 1). In group 3, vWF decreased (median -19%, range -44 to -18). After correction for possible confounders, i.e., age, varying duration of follow-up, and initial level of vWF, the difference in vWF change between groups 1 and 2 remained significant (P = 0.009). Poor glycemic control at baseline, estimated by glycosylated hemoglobin, was a significant predictor of increases in vWF in both group 1 and groups 1 and 2 combined.(ABSTRACT TRUNCATED AT 250 WORDS)

Falsely low serum thyroxine levels caused by interference with the thyroxine assay.

A case of euthyroid hypothyroxinaemia caused by the interference of the patient's serum with the Abbott thyroxine TDx assay is reported. This cause of falsely low serum thyroxine levels is probably rare but possibly underrecognized. Clinical implications are discussed.

Stimulation and suppression of intact parathyroid hormone (PTH1-84) in normal subjects and hyperparathyroid patients.

OBJECTIVE: Because of an overlap between serum PTH values in healthy controls and hyperparathyroid patients we sought to evaluate a short stimulation and suppression test for differentiating the two groups. SUBJECTS: Subjects were 34 patients with primary hyperparathyroidism (PHPT) and 25 healthy controls. DESIGN: After stimulation with intravenous EDTA (10 mg/kg body weight in 5 minutes) blood samples were obtained for up to 15 minutes. After an oral calcium dose of 1 g, blood samples were obtained at 1 and 2 hours. After an intravenous calcium dose (2.5 mg/kg body weight in 30 seconds), blood samples were obtained serially for 20 minutes. MEASUREMENT: Serum PTH(1-84) was measured by a double antibody technique. RESULTS: The intravenous EDTA test resulted in an average 2.6-fold increase of serum PTH(1-84) in hyperparathyroid patients, whereas it increased 10.5-fold in controls. A response was absent in three of 23 patients. There was an overlap in results between patients with mild hyperparathyroidism and controls. The oral calcium dose decreased serum PTH(1-84) in patients to 0.73 and in controls to 0.55 of the basal value, but six of 15 patients and two of 12 controls did not respond. The intravenous calcium test resulted in a drop of serum PTH(1-84) in hyperparathyroid patients to 0.51 and in control subjects to 0.40 of the basal value, and non-responders were not observed. There was a strong correlation between the responses to the EDTA and the calcium infusion tests in the patients (r = 0.97, P less than 0.01). Fasting serum calcium and serum PTH(1-84) showed a positive correlation in PHPT patients (r = 0.75, P less than 0.001) and a negative correlation in control subjects (r = -0.41, P less than 0.05). Based on these relationships, hyperparathyroid patients and controls could be completely separated. CONCLUSION: The wide range of responses to stimulation and suppression tests and the correlation between these responses in hyperparathyroid patients indicate various degrees of autonomy. As the response to these tests is less marked in patients than in controls and both groups still overlap, these tests are not useful for the diagnosis of primary hyperparathyroidism.

Calcitonin gene-related peptide in human obesity.

We studied plasma calcitonin gene-related peptide (CGRP) levels in obese women before (n = 24) and after (n = 13) weight loss, and in normal weight controls (n = 15). Furthermore, the influence of two isocaloric meals (high carbohydrate vs. high fat) on plasma CGRP concentrations was studied. The CGRP concentration in the obese group (32.26 +/- 2.01 pg/ml) was significantly (p less than 0.0001) higher than in the control group (21.64 +/- 0.15 pg/ml). After weight loss (14.3 +/- 0.72% of original weight) CGRP concentrations remained unchanged. Only the high-fat meal caused a significant (p less than 0.02) rise in CGRP levels. Our results indicate that elevated plasma CGRP levels may constitute a primary phenomenon in obese women, and that fat intake may be associated with increased CGRP secretion.

Effect of a single infusion of aminohydroxypropylidene on calcium and bone metabolism in healthy volunteers monitored during 2 months.

Recently, bisphosphonates have been used to prevent postmenopausal bone loss. As the effects of bisphosphonates on normal bone metabolism are unknown, 3-amino-1-hydroxypropylidene-1,1-diphosphonate (APD) was studied in healthy subjects. The effects of a single 20-mg APD infusion on biochemical parameters of calcium and bone metabolism were investigated during 2 months in 10 healthy male volunteers. This single moderate dose of APD reduced biochemical parameters of bone resorption during the time of follow-up. After 2 months, urinary hydroxyproline excretion was still below the basal level. The decreased serum calcium levels did not return to basal values. Biochemical parameters of bone formation, serum alkaline phosphatase and osteocalcin, showed a slight increase during the first month after stimulation of the parathyroids and a corresponding increase in serum 1,25-dihydroxyvitamin D. These formation parameters decreased thereafter, probably representing coupling between bone resorption and bone formation.

Diurnal variation in urinary protein excretion in diabetic nephropathy.

We examined the diurnal variation in urinary excretion rate of albumin, IgG and beta 2-Microglobulin (beta 2-M) in healthy volunteers (n = 24), and in patients with type I diabetes mellitus having normal albumin excretion rate (less than 20 micrograms/min; n = 16), incipient diabetic nephropathy (albumin excretion rate 20-200 micrograms/min; n = 12) and clinical diabetic nephropathy (albumin excretion rate greater than 200 micrograms/min; n = 12). Diurnal variation was defined as [(overnight minus daytime): daytime excretion rate] times 100%. Median diurnal variation in albumin excretion rate in the various groups varied from -32 to -57%, and in IgG excretion rate from -42 to -65%, being not significantly different between the proteins or between the groups. Diurnal variation in beta 2-M excretion rate was similar in healthy volunteers and in patients with normal albumin excretion rate or incipient diabetic nephropathy (median -36 to -43%), but significantly reduced in patients with clinical diabetic nephropathy (median 0%; P less than 0.005), nine of whom had elevated beta 2-M excretion rates, suggesting tubular dysfunction. Except for beta 2-M excretion rate in patients with clinical diabetic nephropathy, the diurnal variations in albumin excretion rate, IgG excretion rate and beta 2-M excretion rate were larger than the diurnal variation in creatinine excretion rate (median -7 to -11%, P less than 0.005). Diurnal variations in albumin excretion rate and IgG excretion rate were highly correlated (r = 0.89, P less than 0.00001). These data suggest that similar mechanisms may account for diurnal variations in albumin excretion rate and IgG excretion rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Excessive secretion of antidiuretic hormone in infections with respiratory syncytial virus.

The association between infections with respiratory syncytial virus and plasma concentrations of antidiuretic hormone was assessed in 48 patients who had been admitted to hospital. The mean (SEM) concentration of antidiuretic hormone was significantly raised in patients with bronchiolitis (9.3 (1.4) ng/l) compared with non-pulmonary respiratory syncytial virus infections that cause apnoea or upper respiratory tract symptoms (6.1 (1.7) ng/l). The highest concentrations of antidiuretic hormone were seen in patients receiving mechanical ventilation (18.0 (6.7) ng/l). There were no differences in mean serum sodium concentrations among the subgroups. Hypertranslucency on chest radiograph or an arterial carbon dioxide tension above 6.67 kPa were associated with a significantly higher concentration of antidiuretic hormone. Increased or normal maintenance fluid intake in children with pulmonary respiratory syncytial virus infections may cause the same symptoms of fluid overload as the syndrome of inappropriate secretion of antidiuretic hormone. Patients with pulmonary respiratory syncytial virus infection, hypertranslucency in chest radiograph, hypercapnia, or mechanical ventilation are at risk for raised concentrations of antidiuretic hormone. Restricted fluid intake and careful monitoring of fluid balance and plasma electrolyte concentrations are therefore necessary in these patients.