The Clinical Observations of the Plasma Human Growth Hormone (HGH) Levels

Abstract

We measured the plasma human growth hormone (HGH) levels by the radioimmunoassay using a double antibody method described by Schalch & Parker. We evaluated HGH secretion from pituitary mainly by plasma HGH response to insulin induced hypoglycemia. As the criteria of fall of blood sugar and rise of plasma HGH levels the following indices were used. The index of fall of blood sugar
= The maximal blood sugar decrements / The time needed for reaching the minimal blood sugar value
(The mean normal range of 12 control subjects was 1.98±0.86) The index of rise of plasma HGH
The maximal plasma HGH increments / The time needed for reaching the maximal plasma HGH level
(The mean normal range of 12 control subjects was 0.63±0.36)
a. The effects of metabolic changes in diabetes mellitus. We investigated the HGH response to insulin in diabetes. The results were as follows :
(1) We observed high fasting blood sugar in diabetes and the lower than normal HGH response to insulin.
(2) There was correlation between decrements of blood sugar and HGH response to insulin although the variations of HGH responses were markedly greater.
(3) We couldn't recognize a correlation between the increments of HGH and hypoglycemic symptoms by insulin.
(4) In severe class of diabetes classified from glucose tolerance curve, the HGH response to insulin was decreased.
(5) In diabetes with nephropathy and/or retinopathy the HGH response to insulin was shown to be lower than in non-complicated diabetes.
(6) The highly obese patients with and without diabetes demonstrated a smaller HGH response to insulin as compared with the non-obese patients. The lean patients also showed a smaller HGH response to insulin.
During above investigations we encountered often presence of insulin antibody and impaired fall of blood sugar by insulin in diabetics, so there have been left certain unsolved problems about methodological viewpoint to evaluate HGH secretion from pituitary in diabetes from these investigations.
b. Clinical studies of plasma HGH in patients with hypothalamopituitary disease
Patients with acromegaly showed elevated fasting HGH levels and especially three cases with diabetes showed significantly elevated values such as 480,470 and 182 mug/ml respectively. In almost all of patients with hypopituitarism, chromophobe adenoma, craniopharyngioma and diabetes insipidus, normal fasting HGH levels were observed. In all cases of six patients with chromophobe adenoma, an impaired or absent HGH response to insulin was observed. In five insulin test examined on four patients with craniopharyngioma, three tests showed good HGH response and two tests no response to insulin. In six insulin tests examined in three patients with diabetes insipidus, the results were variable. We have made a long term follow up study of plasma HGH level in a male acromegalic, 34 years old, who was treated with repeated CO⁶⁰ irradiation. HGH level showed corresponding fall after irradiation.
c. The effects of endocrine changes following administration of corticosteroid and ACTH
In five non-endocrine patients receiving corticosteroid therapy, plasma HGH response to insulin were examined. Four patients showed an impaired or failing plasma HGH response to insulin. Following Friedman's report (Lacet II : 568, 1966), we investigated plasma HGH levels after administration of ACTH. 0.125 or 0.250 mg of β^1-24 ACTH was injected intramuscularly to six subjects. A consistent secretary pattern of HGH from pituitary was not shown for three hours, but a tendency to elevate plasma HGH was shown in four cases. We also administered 1 mg of β^1-24 ACTH-Z. Six of ten cases tested, showed a tendency of elevation of HGH levels from two to six hours after the injection. Two under six subjects administered with commercial ACTH showed also similar pattern.