Diagnosis and Treatment of Pituitary Dwarfism

Abstract

The development of radioimmunoassay for growth hormone made the diagnosis of acromegaly easier and more accurate. Serum growth hormone (GH) concentrations in 31 fasting patients with active acromegaly were all above 15 mμg/ml, while in most cases of normal subjects they were below 5 mμg/ml. Besides cases of acromegaly, abnormally high values were observed in 3 cases of insuloma and in 3 cases of anorexia nervosa. Occasionally, fasting serum GH concentration is high due to the influence of psychological stress or physical exercise. However, in normal subjects, even if such influences cause one specimen to be high, repeated specimens on different days show normal values. On the contrary, cases of acromegaly show high values on all specimens. In addition, high values of fasting serum GH concentration in normal subjects decreased to normal values following administration of glucose, but they remained high in acromegaly.
In 3 patients with acromegaly, serum GH level was followed before and after treatment by ⁶⁰Co irradiation or by surgery. It was observed that GH level decreased with clinical improvement and increased again with relapse.
GH level was also measured in acromegalic patients who had received treatment in the past. Most of the patients who had received radiation therapy showed high values, thus indicating that conventional radiation therapy is incomplete in most cases. In patients who had received surgical treatment, relatively low values were observed; however, only one-third of them showed values below 5 mμg/ml. Among these patients, those whose values were below 10 mμg/ml, showed no clinical symptoms of acromegalic activity, and in most cases no increase of GH level was observed in response to insulin hypoglycemia. In these cases, the total daily GH secretion may be within normal range and they may need no further treatment. This should be studied in the future.
It has been reported that estrogen is beneficial in the treatment of acromegaly. The effect of estrogen on serum GH level was studied in 3 patients with acromegaly and no change of GH level was observed. Therefore, it was concluded that estrogen is effective by suppressing the action of growth hormone in peripheral tissue.
Diagnosis of conventional pituitary dwarfism can be made accurately by measuring the serum GH level by radioimmunoassary, and it is now possible to diagnose even pituitary dwarfism due to selective growth hormone deficiency. Fasting serum GH concentration was measured in variety of cases of dwarfism. Among 14 cases of pituitary dwarfism, GH was not detectable in 10 cases, and in the other 4 cases it was below 1.5 mμg/ml. Although in most of cases non-pituitary dwarfism, GH was detectable, in some cases it was undetectable. In the latter cases, examination of growth hormone response to insulin hypoglycemia is very effective in differentiating pituitary dwarfism from other kinds of dwarfism. In all normal subjects and cases of non-pituitary dwarfism, significant increase of serum GH level was observed. No increase was observed in 18 cases of pituitary dwarfism. Although a definite response was observed in 4 cases of thyroid dwarfism and in 6 cases of Turner's syndrome, it was a relatively weak response compared with that of normal subjects. Growth hormone response to arginine injection is also useful in differentiating pituitary dwarfism from non-pituitary dwarfism. Definite and significant increases of serum GH concentrations were observed in 5 normal subjects, while no increase was observed in 4 cases of pituitary dwarfism.
Parker et al. have reported serum GH increases in some cases of pituitary dwarfism in response to either insulin hypoglycemia or arginine infusion. A 20-year-old boy clinically suggesting pituitary dwarfism was observed. Although this patient showed a moderate serum GH increase in response to insulin hypoglycemia,