Thyroid hormone concentrations in Nepal: a study of potential Gurkha army recruits. The effect of changes in diet.

A group of non goitrous, potential Gurkha army recruits were tested in Nepal for serum free triiodothyronine (fT3), free thyroxine (fT4) and thyrotropin (TSH) concentrations. Twenty-five percent of the men were recruited into the army and urine samples taken for analysis of iodine and creatinine. Twenty per cent of the recruits underwent thyrotropin releasing hormone (TRH) stimulation tests. After ten months basic training on a diet considered to be iodine sufficient, the tests were repeated on the same men. The results were also compared to army recruits in the UK. All the potential Gurkha recruits had higher serum levels of thyroid hormones than the UK recruits. Some regional differences were found with those men from the Western recruiting depot having lower fT4 and higher TSH concentrations. Urinary iodine and creatinine concentrations showed evidence of slight relative malnutrition and iodine deficiency which was more pronounced in the Western depot. TRH stimulation tests showed no evidence of thyroid dysfunction but highlighted the differences between the Eastern and Western groups. After ten months on an iodine sufficient diet the serum thyroid hormone concentrations became closer to those of the UK recruits, showing any differences to be reversible. The results from the two Gurkha groups became similar which was reflected in the urine analysis results.

The synthesis, release and action of leukotrienes in the isolated, unstimulated, buffer-perfused rat heart.

When the perfusion medium of an isolated, non-recirculating, Langendorff rat heart is changed from Krebs buffer to coronary effluent, a significant vasoconstriction (23%, P less than 0.005) is observed. In this study we have investigated the involvement of leukotrienes in this phenomenon. We have extracted and quantified leukotrienes C4, D4 and E4 in samples of coronary effluent taken at different times during the first 2 h of perfusion; the total amounts released during this time were 9, 5 and 32 pmol of LTC4, LTD4 and LTE4 respectively. We have used two different methods to prevent the action of the effluent leukotrienes on the heart. Firstly, we have blocked the leukotriene receptors in the heart, with FPL 55712 (3.8 microM), during perfusion with effluent and, secondly, we have perfused with coronary effluent which was collected in the presence of a leukotriene synthesis inhibitor, AA861 (1 microM). The addition of FPL 55712 to the effluent decreased the normally observed vasoconstriction such that after 30 min the coronary flow rate (CFR) was 114 +/- 3% (n = 6) compared with 66 +/- 1% (n = 7) with effluent alone (P less than 0.005). Effluent collected in the presence of AA861 also caused a decrease in the normally observed vasoconstriction such that by 30 min the CFR was still 88 +/- 2% (n = 6, P less than 0.005 compared to controls). We have confirmed the proposed involvement of leukotrienes in the effluent-induced vasoconstriction by investigating the effect of a mixture of the synthetic leukotrienes C4, D4 and E4, when each of them was present at the same concentration as measured in the coronary effluent; the vasoconstriction observed was superimposable upon that seen with effluent. This vasoactive effect of the leukotriene mixture was not secondary to a change in contractility, since this only decreased to 97 +/- 5% (n = 9) during the 30 min of the leukotriene infusion. Finally, we have studied the effects of the same two leukotriene blockers in normal, buffer-perfused hearts after an initial perfusion of either 30 or 120 min. Application of either AA861 or FPL 55712 resulted in a dramatic vasodilatation (25 to 45% increase), a larger effect always being observed after the shorter initial period of perfusion. Our conclusions are two-fold. Firstly, isolated, buffer-perfused rat hearts synthesize leukotrienes C4, D4 and E4 in considerable amounts and release them into the coronary effluent and secondly, the coronary flow rates of isolated, buffer-perfused rat hearts are partly controlled by the action of internally produced leukotrienes.

Serum concentrations of alkaline phosphatase isoenzymes and osteocalcin in normal pregnancy.

We measured serum alkaline phosphatase isoenzymes and osteocalcin levels in 40 healthy women at 4-week intervals throughout uncomplicated pregnancies and 6 weeks after delivery in 17 women. Serum bone alkaline phosphatase was significantly higher in the third trimester than in early pregnancy (P less than 0.001), and this elevation was still apparent at the end of the puerperium, suggesting increased bone turnover. Serum osteocalcin was not detected (less than 0.2 micrograms/L) after the first trimester in the majority of women, and it reappeared within 48 h after delivery. The disappearance of osteocalcin after the first trimester and its rapid reappearance after delivery suggest placental clearance of this peptide. We conclude that serum osteocalcin measurements cannot be used as a marker of bone metabolism during pregnancy.

51Cr-EDTA/99Tcm-MDP ratio: a simple non-invasive method for assessing renal osteodystrophy.

We have used 99Tcm-MDP to develop a measure of overall skeletal activity for use in renal disease. The method utilizes the relative clearances of 99Tcm-MDP and 51Cr-EDTA from the blood after simultaneous injection. This is expressed as a ratio and the upper limit in normals is 1.4. This ratio has been evaluated in 42 patients with chronic renal failure and compared with appearances of left-hand radiographs. The ratio was elevated in these patients and the level corresponded to the degree of severity of the subperiosteal resorption. Similarly, there was a close correlation between the ratio values and the serum alkaline phosphatase measurements and parathyroid hormone values. Thirty-three patients had sequential studies performed at intervals of up to 2 years. Twenty-one patients showed no change on clinical, biochemical or bone scan evaluation. Of these, only one patient showed a change in ratio value of greater than 20%. Twelve patients showed evidence of change based either on clinical, biochemical or bone scan alteration and all 12 patients showed changes in ratio values greater than 20%. The 51Cr-EDTA/99Tcm-MDP ratio appears to offer not only a single plasma sample method for the detection and evaluation of renal bone disease, but our results also suggest that it may be valuable in the follow-up of these patients.

Biochemical prediction of response of bone metastases to treatment.

Assessment of response of skeletal metastases to systemic therapy is currently dependent on radiological evidence of bone healing. We have performed a prospective study of additional response criteria in patients with progressive bone metastases from breast cancer. Changes in these potential markers of response were correlated with the radiological response and the time to treatment failure (TTF). Successful systemic therapy typically led to a transient increase in osteoblast activity ('flare'), a reduction in osteoclast activity and symptomatic improvement. After 1 month a greater than 10% rise in serum osteocalcin (BGP) and alkaline phosphatase bone isoenzyme (ALP-BI) and a greater than 10% fall in urinary calcium excretion were seen in 14/16 patients with radiographic evidence of bone healing (UICC partial responders). In comparison similar biochemical changes at 1 month were seen in only 4/20 patients with progressive disease (P less than 0.001). The predictive value and diagnostic efficiency (DE) of changes at 1 month in biochemical measurements and symptom score has been calculated. The combination of a greater than 10% rise in ALPBI and BGP and a greater than 10% fall in urinary calcium excretion had a DE of 89% for discriminating response from progression, 88% for response from non-response (progressing + no change patients), and 76% for TTF of greater than 6 months from TTF of less than 6 months. Serum calcium, tartrate resistant acid phosphatase (TRP), urinary hydroxyproline excretion and bone scan changes were unhelpful in discriminating between patient groups. Independent confirmation is needed, but our results suggest there are reliable alternatives to plain radiography in the early assessment of response of bone metastases to treatment.

Bone scan flare predicts successful systemic therapy for bone metastases.

Changes in osteoblast function, assessed by serial bone scans and serum alkaline phosphatase bone isoenzyme (ALP-Bl) and osteocalcin, have been studied in 53 patients receiving systemic therapy for bone metastases from advanced breast cancer. In 12/16 patients with healing of lytic disease on x-ray a paradoxical deterioration in the bone scan appearances after 3 mo treatment was seen. This was characterized by increased activity in baseline lesions and the appearance of new foci of tracer uptake; changes which are indistinguishable from progressive disease. After 6 mo successful treatment the bone scan improved with reduced tracer uptake and no new lesions since the 3-mo scan. New lesions appearing after 6 mo indicated progressive disease. These changes are attributed to a flare in osteoblast activity induced by successful systemic therapy and confirmed by a transient rise in osteocalcin and ALP-Bl. After 1 mo of treatment 15/16 responders showed a rise in both parameters compared with only 5/23 nonresponders (p = less than 0.001). The flare response is the rule rather than the exception after successful systemic therapy for bone metastases. The appearance of new lesions or increasing activity in known lesions during the first 3 mo is as likely to herald radiological response as disease progression.

Osteocalcin: a potential marker of metastatic bone disease and response to treatment.

Serum osteocalcin (BGP) is an osteoblast product that probably reflects the rate of bone formation. It is a potential marker of skeletal metastases and, to investigate this, BGP was measured by radioimmunoassay in the serum of normal subjects and patients with breast or prostate cancer. Significantly higher levels were found in patients with metastatic bone disease in comparison to both normal subjects (P less than 0.001) and patients with non-metastatic cancer (P less than 0.05 for breast cancer and less than 0.001 for prostate cancer). The range of values was wide. Levels were higher in sclerotic than lytic bone metastases (P less than 0.01) and lower in patients with hypercalcaemia (P less than 0.001). Serial measurements of BGP were made in 53 patients with skeletal metastases from breast cancer receiving systemic therapy. At 1 month BGP rose by greater than 0.5 ng/ml in 15/16 responding patients compared with 7/23 patients with progressive disease (P less than 0.01). Responding patients also showed a rise in the bone isoenzyme of alkaline phosphatase and a paradoxical deterioration in the bone scan appearance, both reflecting a flare in osteoblast activity. The early increase in responding patients was followed by a gradual decrease over subsequent months as the osteoblast reaction induced by systemic therapy subsided. We conclude that BGP measurements reflect a wide variability of bone formation rates in metastatic bone disease. Bone formation was usually increased, particularly when metastases were sclerotic in appearance, but in patients with hypercalcaemia the low BGP levels suggest uncoupling of bone resorption and formation. Serial measurements of BGP may be useful in monitoring response to treatment.

A single plasma sample method to assess disease activity in patients with bone metastases from carcinoma of the prostate.

A single blood sample method was used to measure total skeletal activity during routine radionuclide bone scans in 114 patients with known carcinoma of the prostate. The method is based on the measurement of radioactivity in plasma after administration of 99mTc MDP and 51Cr EDTA, providing an assessment of total skeletal activity independent of renal function. The results showed a significant elevation of skeletal activity in patients with untreated bone metastases when compared with patients with no metastatic spread. Significant elevation with increasing extent of metastases was also shown, the highest activity being in patients with diffuse metastatic spread (superscan). Patients with treated metastatic disease showed significantly lower skeletal activity than patients with untreated bone metastases. The method requires the use of two radiopharmaceuticals injected as a mixture and potential errors may arise from pharmaceutical instability. In addition, elevation of total skeletal activity may be caused by coexistent metabolic bone disease. The results suggest that the measure may provide quantitative information in the assessment of the activity of bone metastases from prostatic carcinoma.

Chromium 51 EDTA/technetium 99m MDP plasma ratio to measure total skeletal function.

A method is described for the quantitation of total skeletal activity during bone scans. The method requires a single plasma sample only, taken at the time of imaging. The ratio of % injected dose of 51Cr EDTA to that of 99Tcm MDP is calculated from this sample following combined injection of the two radiopharmaceuticals. The 51Cr EDTA level corrects for the glomerular filtration of 99Tcm MDP. Using this method, which only requires a gamma counter, significant differences from normal controls have been shown in patients with osteomalacia, renal osteodystrophy, Paget's disease and hypercalcaemia. The method provides routine quantitative data to add to the imaging information in the bone scan.

Serum triiodothyronine: clinical experience with a new radioimmunoassay kit.

A new kit for measuring total serum triiodothyronine (T3) by radioimmunoassay ('T3 RIA'; Radiochemical Centre, Amersham) was evaluated using sera from 1114 patients and normal controls. The kit performed reliably with intraassay and interassay variability figures of 3.9% and 9.3%, respectively, at 'medium' concentrations of T3. A T3 measurement could be obtained conveniently within 18 h after overnight incubation at room temperature. There were no critical steps dependent on time or temperature. Serum T3 values showed no significant sex difference. There was no significant change in mean serum T3 between the ages of 15 and 69 years, but it fell by 0.15 nmol/l for every 5 years beyond the age of 70. Mean serum T3 (+/-SD) for 335 normal euthyroid subjects ages 15-69 years was 2.11+/-0.46 nmol/l (range: mean+/-2 SD = 1.19-3.03 nmol/l). 64% of pregnant euthyroid women and 12% of those taking oral contraceptives had elevated serum T3 levels, as did all hyperthyroid patients, apart from one with T4 toxicosis. Overlapping T3 values from hyperthyroid patients and euthyroid subjects with elevated concentrations of thyroid binding proteins could be separated completely by two correction techniques which related total serum T3 to the corresponding T3 resin uptake test, viz an 'augmented free T3 index', or a map plot of T3 vs T3 resin uptake. A 25% incidence of T3 toxicosis was observed. One hyperthyroid patient with T4 toxicosis, and seven euthyroid patients with 'biochemical T4 toxicosis' were investigated. 73% of moderately and 30% of severely hypothyroid patients had normal serum T3 levels. This overlap was not reduced by applying correction techniques. Our studies demonstrate the value of serum T3 measurements in screening for and diagnosing hyperthyroidism. As T3 measurements become more widely available, it would seem reasonable to subclassify hyperthyroid patients into three types: those with 'T3/4 toxicosis', 'T3 toxicosis' and 'T4 toxicosis'.

A rational approach to "in vitro" thyroid function testing.

A system of "in vitro" thyroid function testing is proposed whereby laboratory staff select the most appropriate screening test depending on the information supplied by the clinician. Total serum triiodothyronine (T3) or thyroxine (T4) are used for screening as appropriate. In borderline cases, secondary tests are performed automatically according to a flow chart. This system improves efficiency and is cost effective, saving approximately 1,800 pounds annually in a laboratory handling about 5,000 requests for thyroid function tests each year.

Persistent pancreatic glucagon but not insulin response to arginine in pancreatectomized dogs.

Effects of total pancreatectomy on plasma glucagon, insulin and glucose responses to arginine were determined in 5 dogs. Portal vein and femoral artery samples were obtained in response to an arginine infusion (10 g/30 min) prior to, 1 h, 1 day and 1 week after pancreatectomy. Glucagon was measured using pancreatic-specific antiserum 30K (Unger, Dallas). Before pancreatectomy arginine significantly increased portal vein glucagon from 373 plus or minus 36 to 595 plus or minus 31 pg/ml and femoral artery levels from 233 plus or minus 28 to 342 plus or minus 74 pg/ml. Portal vein and femoral artery insulin concentrations of 74 plus or minus 21 and 17 plus or minus 3 muU/ml increased significantly to 173 plus or minus 64 and 31 plus or minus 7 muU/ml. Glucose levels did not change. One h after pancreatectomy, portal vein glucagon decreased to 121 plus or minus 15 pg/ml but increased to 230 plus or minus 42 pg/ml after arginine. Elevated blood glucose and the necessity for insulin treatment established the adequacy of pancreatectomy. Furthermore portal vein insulin levels were undetectable and unresponsive to arginine or a combination of glucose, glucagon, and tolbutamide 1 week after pancreatectomy. One day after pancreatectomy arginine significantly increased portal vein glucagon from 343 plus or minus 42 to 776 plus or minus 152 pg/ml. One week after pancreatectomy basal glucagon values were 374 plus or minus 30 in the portal vein and 360 plus or minus 49 in the femoral artery and responded to 1226 plus or minus 641 and 825 plus or minus 270 pg/ml, respectively, with arginine. Chromatography of plasma from one pancreatectomized dog on Sephadex G-50 after arginine stimulation revealed that much of the material cross-reacting with antibody 30K was eluted from the column earlier than either 125I-insulin or 125I-glucagon. In contrast, peak glucagon activity in plasma obtained from a normal human given arginine eluted from the column between the peak of 125I-insulin and 125I-glucagon; glucagon added to human plasma also was recovered in this same area between the 125I-insulin and 125I-glucagon peaks. These results suggest that some of the material that reacted with 30K antibody and which increased after pancreatectomy in response to arginine has a molecular weight greater than pancreatic glucagon. At autopsy no pancreatic tissue could be identified. Thus, after pancreatectomy, validated by absent insulin responses, the glucagon response to arginine was normal or increased. Since arginine is not thought to increase intestinal glucagon-like immunoreactive material, the source and nature of the material measured as glucagon after pancreatectomy is unknown, but may be important to any understanding of plasma glucagon measurements.