A. D. Wright

SERUM-GROWTH HORMONE AND GLUCOSE INTOLERANCE IN RENAL FAILURE

Abstract Serum-growth-hormone (G.H.) measurements during oral glucose-tolerance tests were done on forty-one patients with chronic renal failure, seven patients with nephrotic syndrome, and fifty controls. Of the patients with chronic renal failure, 54% had impaired glucose tolerance (2-hour blood-sugar greater than 120 mg. per 100 ml.) and G.H. levels were raised in 49%, but not significantly among those with impaired glucose tolerance. In chronic renal failure, the Serum-G.H. level correlated directly with the serum creatinine and inversely with serum-albumin. It is suggested that protein malnutrition may be an important factor determining the raised levels of G.H. in renal failure.

Metabolic Response to Oral Glucose in Healthy South African White, Indian, and African Subjects

The response of serum insulin, growth hormone, plasma free fatty acids, triglycerides, and blood glucose to an oral glucose load was investigated in healthy White, African, and Indian subjects. Serum cholesterol, uric acid, platelet adhesiveness, and urine insulin clearance were also measured. Each racial group responded differently. Most striking were the differences between Africans and Whites; despite similar mean blood glucose values at all times during the test, the Africans had lower serum insulin levels, a lower urine insulin clearance, a much greater rise of growth hormone, a more definite and prolonged suppression of free fatty acid release, lower serum cholesterol and uric acid levels, and a trend towards lower plasma triglyceride values. The Indians tended to resemble Whites rather than Africans with respect to their insulin, growth hormone, cholesterol, and triglyceride levels. Their glucose tolerance was decreased compared with that of the other two groups, but suppression of their free fatty acids was enhanced. Platelet adhesiveness was similar in all three groups. The reasons for these differences are unknown, but must be related to genetic and environmental differences among the three races.

Serum Growth Hormone Levels and the Response of Diabetic Retinopathy to Pituitary Ablation

Serum growth hormone levels were measured during insulin tolerance tests in 36 patients after yttrium-90 pituitary implantation for diabetic retinopathy. The response of the new blood vessels was more clearly related to loss of growth hormone function than was the improvement of retinal haemorrhages and microaneurysms. The overall response of the retinopathy was greatest when growth hormone function was lost. Since the loss of growth hormone function was related to the loss of other aspects of anterior pituitary function, a unique role of growth hormone in the response of diabetic retinopathy to pituitary ablation could not be established.

Calcium metabolism in acromegaly.

A total of 78 acromegalic patients were studied before and after treatment by yttrium-90 needle implantation. Among the untreated patients 16% had a borderline or raised serum calcium. In half of these patients the serum calcium fell to normal after remission of their acromegaly. In the others the hypercalcaemia was due to associated proved or probable hyperparathyroidism. A downward trend of the serum calcium was noted even in the normocalcaemic patients with remission of their disease. Only 20% of untreated patients had a raised serum phosphate, and follow-up showed this measurement to be a poor index of disease activity. Net calcium absorption and calcium balances in five patients in this series and 12 others from the literature were essentially normal for their given level of calcium intake. No patient showed definite radiological evidence of osteoporosis and vertebral fractures. Bone uptake rate of calcium-47 and stable strontium was raised in the untreated state in all nine patients studied. The 24-hour strontium space was raised in 73% of untreated patients and fell to normal after treatment in all the retested patients in whom it was high initially.

Serum growth hormone levels and size of pituitary tumour in untreated acromegaly

Serum levels of growth hormone were measured in 84 untreated acromegalic patients. The range of mean level during a glucose tolerance test was 8 to 1,860 ng./ml. and was lognormally distributed. Mean level was reproducible and correlated moderately well with maximum sellar area on lateral tomography. The hormone level was more responsive to oral glucose and insulin-induced hypoglycaemia in patients with smaller tumours. Attention is drawn to limitations of plain radiographs in assessing the size of a pituitary tumour. Suprasellar tumour extensions may be present in patients without visual field defects.

Carbohydrate Tolerance, Growth Hormone and Insulin Levels in Mongolism

Plasma insulin and growth hormone levels were measured during glucose and insulin tolerance tests in comparable groups of children with mongolism and other causes of mental deficiency. Low plasma‐insulin levels in response to a glucose load were found in both groups and also in normal children when compared with adults.

FASTING BLOOD-SUGAR AND SERUM-GROWTH-HORMONE IN HYPOPITUITARY DIABETICS

Abstract Among 21 ketosis-prone diabetics, fasting blood-sugar (F.B.S.) levels at 5.30 and 7.30 A.M. (i.e., 8-10 hours after food and 12-14 hours after insulin) revealed a rise (F.B.S. increment) over these 2 hours of 76 mg. per 100 ml.±11 (mean±S.E.). This rise exceeded 42 mg. per 100 ml. in 18 out of 21 patients. Among 29 similar patients, after pituitary ablation by 90 yttrium for diabetic retinopathy, the same F.B.S. measurements showed a lower increment of 42 mg. per 100 ml.±6 (mean±S.E.). In only 3 out of 21 patients did this rise exceed 76 mg. per 100 ml. Subgrouping of the pituitary-ablated diabetics (who had by plan received different 90 yttrium doses) into three grades, by tests of pituitary function, revealed no change in the F.B.S. increment in those slightly ablated (75 mg. per 100 ml.±14, mean±S.E.) but considerable lowering in those maximally ablated (24 mg. per 100 ml.±6, mean±S.E.). In 24 out of 31 pituitary-ablated diabetics the maximum growth-hormone level measured during insulin-induced hypoglycaemia revealed reduced or lost growth-hormone secretory capacity, corresponding with other tests of pituitary function. The insulin management of hypopituitary diabetics should allow for their tendency to a stable F.B.S. in addition to their increased sensitivity to insulin. In most maximally ablated patients blood-sugar control was satisfactory when they were given only isophane insulin before breakfast and soluble insulin before supper.