Plasma Human Growth Hormone Levels Research Articles

Decrease in human growth hormone (HGH) levels during transsphenoidal surgery for acromegaly as a guide for prognosis.

To evaluate the clinical significance of human growth hormone (HGH) dynamics during transsphenoidal microsurgery for acromegaly, serial HGH levels during the surgery were compared with the post-operative basal HGH levels in 15 acromegalic patients, retrospectively. In all patients, in whom the HGH level immediately after tumor resection was reduced below 5 ng/ml or the decreasing rate which stood for the magnitude of decrease of HGH during resection procedure was above 80%, postoperative permanent HGH levels fell to below 5 ng/ml, namely, within the normal range. The rapid radioimmunoassay (RIA) of HGH was developed by the use of high affinity antibody in order to inform the surgeons of plasma HGH levels quickly during the surgery. It is now possible to know HGH levels about 1 hour after submitting the samples. It was verified that HGH levels measured in the rapid RIA correlated well with those obtained in the conventional way. The rapid RIA method was applied to 6 patients and the correlation between HGH levels during the surgery and post operative levels was also studied prospectively. The results were essentially identical to those in a retrospective study. It was suggested that the HGH level immediately after tumor resection and the extent of the decrease in HGH during the resection procedure were good indicators of the prognosis of surgical results in acromegaly and the rapid RIA method was useful in order to judge HGH levels quickly during the surgery.

Basal plasma HGH and cortisol levels and the effect of clonidine administration in female migrainous patients.

Clonidine, a central alpha-adrenergic agent and prophylactic antimigraine drug is known to stimulate human growth hormone (HGH) release and to suppress cortisol secretion. A possible association between basal hormonal levels and response to either acute clonidine test or chronic treatment in female migrainous patients was investigated. 15 females, aged 18-43 years, suffering from migraine, underwent an acute clonidine test by administration of a single oral dose of 0.15 mg. High basal HGH levels (greater than or equal to 9 ng/ml) were observed in 6 patients, while the other 9 patients demonstrated normal low basal HGH levels. Acute clonidine administration induced a marked rise of HGH in 8 of the 9 patients with low basal HGH. In 4 of the 8 responders HGH levels exceeded 20 ng/ml and 3 subjects reached the acromegalic range (greater than 90 ng/ml). The mean response in this group was higher than in a reference group consisting of children and adolescents. It is suggested that the basal hypersecretion and the hyperresponsiveness of HGH to clonidine provocation test in some migrainous patients results from a hypersensitivity of the central alpha-adrenergic receptors. 12 of the 15 females were treated for 10 weeks with clonidine at gradually increased doses of 0.05 mg/day up to a maximal dose of 0.15 mg/day. A marked suppressive effect on cortisol secretion was observed in the migrainous patients after acute and chronic administration of clonidine. No correlation was observed between HGH and cortisol response to acute or chronic clonidine administration and the prophylactic effect of clonidine on migraine.

Effect of neurosurgical operations on the neurohypophyseal function (author's transl)

Following neurosurgical operations, diabetes insipidus or SIADH is often observed, the former characterized b) polyuria, hypernatremia and a low plasma level of arginine vasopressin (AVP) ; and the latter by hyponatremie and a high plasma level of AVP. In this study, plasma levels of AVP, human growth hormone (HGH), nicotine stimulated neurophysine (NSN), estrogen stimulated neurophysine (ESN), sodium and creatinine; plasma osmolarity and urine output were measured during neurosurgical operations. Plasma levels of AVP, NSN, ES? and HGH were assayed by radio-immunoassay. Plasma AVP and NSN rose to the highest level towards the end of each operation in parallel with the change of plasma HGH levels. Significant correlation was observed betweerr the plasma levels of AVP [y: (pg/ml)] and NSN [x: (ng/ml)]; y=2.lx+6.5 (r=0.64, P<0.01). It is thought that the elevation of plasma levels of AVP and NSN towards the end of the operation is mainly caused by surgical stress. There were no significant correlations between the level of AVP in plasma and plasma osmolarity or between the former and change in blood pressure during the period of observation. It is suggested that these two factor: which are important in regulating the AVP level under physiological conditions may not be critical in the elevation of AVP by neurosurgical procedures. From the course of AVP levels in plasma, it was considered that surgical stress after manipulation of the dura mater may be the main factor evoking the course of AVP release, resulting in retention of free water.

Comparison of the changes in plasma human growth hormone (HGH) and immuno-reactive glucagon (IRG) after intravenous and subcutaneous injection of glucagon.

Ten healthy male volunteers were studied to compare the effectiveness of intravenous and subcutaneous injections of 1 mg of glucagon on HG secretion. Plasma HGH level rose to a peak of 6 ng/ml or greater 120 minutes after the subcutaneous injection of glucagon (sc glucagon) in all subjects, whereas the intravenous injection of glucagon (iv glucagon) caused comparable increments in plasma HGH in only six out of ten subjects. Furthermore, in comparison to those in sc glucagon the periods required to show maximum responses were less consistent in iv glucagon. Plasma IRG levels reached a peak of 102.4+/-22.6 ng/ml at two minutes following iv glucagon, and a peak of 3.33+/-1.08 ng/ml at 15 minutes following sc glucagon. These fell to initial levels at 60 minutes and at 180 minutes, respectively. There was no definite correlation either between the magnitudes of changes in plasma IRG and HGH levels or between the velocities of decrement in blood sugar and HGH responsiveness. Judging from its simplicity and reproducibility it may be concluded that sc glucagon is more suitable for a clinical provocative test of HGH release than is iv glucagon. In regards to the mechanism of glucagon-induced HGH release, neither glucagon per se nor the fall of blood sugar after hyperglycemia was assumed to play any major role. The sustained elevation of plasma IRG for a certain period might be responsible for the glucagon-induced HGH release.

Effect of pituitary ultrasonic treatment on plasma human growth hormone levels in diabetic retinopathy and acromegaly.

Sixteen diabetic patients presenting advanced retinopathy and 6 patients with acromegaly underwent ultrasonic treatment (UST) of the pituitary, according to Arslan’s method. In the diabetic retinopathy patients, circadian variations of plasma human growth hormone (HGH) levels were studied as well as the response to insulin stimulation, previous to and 7 days after the operation. Five patients were also studied 3 months post-ultrasonic treatment. Preoperative HGH plasma levels were normal and no reduction was observed following operation. Acromegalic patients were rested for oral glucose tolerance and insulin response, before and 7 days after operation. High pre-operatory HGH levels fell appreciably after operation, but the reduction was not significant. Our data demonstrate that high plasma levels of HGH are not always found in diabetes and that even after UST of the pituitary, there does not seem to be a relationship between degree of pituitary inhibition and clinical results. On the other hand, ultrasonic treatment of the pituitary in acromegalic patients determines partial hypophyseal inhibition.

Plasma growth hormone response to insulin-induced hypoglycemia in diabetes mellitus.

Plasma human growth hormone (HGH) response to insulin-induced hypoglycemia was studied in patients with diabetes mellitus and age and sex matched normal subjects. The diabetics comprised two groups: (a) those with retinopathy, (b) those without retinopathy. Adequate hypoglycemia (50% or a greater fall in fasting blood glucose) was achieved by i.v. administration of insulin 0.1 U/kg body weight in normal subjects and 0.2 U/kg in diabetics. Mean fasting plasma HGH levels did not differ significantly between control subjects (1.39 ± 0.25 SEM, ng/ml), diabetics without retinopathy (1.55 ± 0.25) and diabetics with retinopathy (1.81 ± 0.6). There was a significant rise in plasma HGH, following insulin-induced hypoglycemia in all three groups. When mean Δ HGH or sum HGH value in different groups were compared, no significant difference was observed. However, mean HGH-hypoglycemia index (Δ HGH · 100/nadir blood glucose) was significantly lower in the two diabetic groups as compared to that obtained in control subjects, but it was identical in diabetics with or without retinopathy. In 32% of diabetic patients abnormal blood glucose and plasma HGH responses were observed.

Daily production and metabolic clearance of growth hormone in juvenile diabetes mellitus.

Daily production (PR) of human growth hormone (HGH) was calculated in patients with juvenile diabetes and control subjects by determining metabolic clearance rate (MCR) of131I HGH, at equilibrium, and mean endogenous HGH levels throughout a 24 h day. Half hourly sampling or a constant withdrawal pump were used to obtain an integrated mean endogenous HGH level. MCR (liters/day) was significantly reduced in all diabetic subjects both in absolute terms (96 ± 15 vs 274 ± 37) and relative to surface area (62 ± 8 vs 171 ± 21) (p < 0.01). Mean HGH levels were 8.4 ng/ml in the diabetics and 5.5 ng/ml in age matched controls. Daily HGH PR in the diabetic subjects (339 to 1365 μg/day) did not exceed values in the control subjects (1005–1426 μg/day). The results indicate that the elevated plasma HGH levels and increased HGH response to stimuli observed in diabetes, reflect reduced metabolic clearance, rather than increased pituitary secretion.

Diurnal variation in glucose tolerance and in insulin secretion in man.

The changes in blood glucose and plasma free fatty acid (FFA), insulin, and human growth hormone (HGH) concentrations in response to oral and intravenous glucose and intravenous insulin were measured at 7 a.m. and 7 p.m., on both occasions after a ten hour fast, in thirteen normal males and two juvenile diabetics. Basal concentration of plasma FFA was lower and that of plasma insulin higher in the morning than in the evening. Blood glucose and plasma HGH levels did not differ at these times. In the normal subjects, glucose tolerance was diminished and plasma insulin response was delayed in the evening. The delay was significantly less with intravenous glucose than with oral glucose. When compared with the usually accepted criteria for diagnosis of diabetes mellitus, the normal subjects responded in the evening as mild diabetics. Two juvenile-onset diabetics, who had virtually no increase in plasma insulin concentrations after ingestion or injection of glucose, showed no diurnal variation in glucose tolerance. No diurnal variation was seen in the blood glucose response to intravenously injected insulin or in the plasma clearance rate of insulin; these findings suggest that impairment in glucose tolerance in the evening is due to diminished early insulin response to glucose, rather than to abnormal handling of glucose or insulin. The effect of tolbutamide, phentolamine, and theophylline on the diurnal variation of glucose tolerance was studied. In four subjects, intravenous injection of tolbutamide induced a greater insulin response and a greater fall in the blood glucose concentration in the morning than in the evening. The disappearance rate of intravenously injected glucose and both early and delayed insulin responses to the glucose were enhanced to a much greater degree in the morning than in the evening by the simultaneous intravenous injection of tolbutamide. Intravenous infusion of phentolamine, an alpha-adrenergic blocking agent, in five subjects failed to influence responses to intravenous injection of glucose. Intravenous infusion of theophylline, which inhibits cyclic 3′5′-adenosine monophosphate phosphodiesterase activity, in five subjects potentiated the plasma insulin response to intravenous glucose in the evening but not in the morning; the substance did not influence the disappearance rate of glucose.

Routine ultramicro-measurement of human growth hormone in plasma by solid-phase radioimmunoassay.

A method for the ultramicro-measurement of human growth hormone (HGH) in plasma based on the solid-phase radioimmunoassay (RIA) using antibody-coated disposable microtiter trays was described. This method is simple, rapid and inexpensive, and particularly useful for ultramicro-measurement of plasma HGH levels in large numbers of plasma samples.The lower limit of sensitivity for purified HGH was 25pg/ml (P<0.05). The precision of the measurement of HGH in plasma has been calculated, and the quantitative sensitivity of the method derived from the results given by its routine use was 56.8pg/ml (P<0.05). The HGH level of normal pooled plasma in 10 replicates was 1, 515pg/ml (±126;1SD), and the coefficient of variation was 8.3%.The mean basal plasma HGH level after an overnight fasting in 23 normal males was 2, 100pg/ml (±1, 491; 1 SD) by this method and 2, 036pg/ml (1, 643; 1 SD) by double-antibody RIA, and in 23 normal females, 2, 589pg/ml (±1, 189; 1 SD) and 3, 300 pg/ml (±1, 690; 1 SD) respectively; there was no statistically significant difference between the basal HGH level obtained from this method and that from double-antibody RIA in normal subjects. On the other hand, the mean basal plasma HGH level after an overnight fasting in 21 hypopituitary patients was 484pg/ml (±282; 1 SD) by this method, and this value was significantly lower (P<0.001) than 1, 376pg/ml (±498; 1 SD) by double-antibody RIA. These data show that determination of basal plasma HGH levels by this method is of much value in the diagnosis of hypopituitarism.

Human prolactin. Evidence obtained by the bioassay of human plasma.

SUMMARY Single plasma samples from 27 control subjects and from 18 women in early lactation have been assayed for lactogenic activity using a semi-quantitative rabbit mammary gland organ culture method. Tests with a variety of anterior pituitary, posterior pituitary, placental and steroid hormones have shown the method to be specific for prolactin and for prolactin-like hormones such as human growth hormone (HGH) and human chorionic somatomammotrophin (HCS). Twelve of the 18 samples from women in early lactation gave positive lactogenic responses, while only one of the control samples did so. Plasma HGH levels were measured by radioimmunoassay. The levels of HGH in the medium, resulting from addition of plasma, were in all cases below the limits of sensitivity of the assay. The conclusion that human prolactin immunologically distinct from HGH is being measured is supported by the failure of antiserum to HGH to affect the in-vitro lactogenic response to plasma. Assay of fractions prepared from plasma by gel filtration suggests a molecular weight of approximately 20000 for the lactogenically active material.

EFFECTS OF NEUROLEPTANAESTHESIA ON PLASMA LEVELS OF GROWTH HORMONE AND INSULIN

SUMMARY The effects of neuroleptanaesthesia and surgery on carbohydrate and fat metabolism were studied in twenty-five patients by determining plasma human growth hormone (HGH), insulin, blood glucose and free fatty acids (FFA). The neuroleptanaesthesia consisted of droperidol, pethidine and nitrous oxide alone for 45 minutes and surgery increased significantly plasma HGH, insulin and blood glucose levels. Plasma FFA levels were insignificantly elevated. The clinical significance of this temporary state of glucose intolerance is also discussed.

EFFECTS OF SPINAL ANAESTHESIA AND SURGERY ON CARBOHYDRATE AND FAT METABOLISM IN MAN

SUMMARY The effects of spinal anaesthesia and surgery on carbohydrate and fat metabolism were studied in thirty patients by determining plasma concentrations of human growth hormone (HGH), insulin, blood glucose and free fatty acids (FFA). Hyperbaric spinal anaesthesia with lignocaine or quatacaine alone and subsequent surgery did not influence the plasma HGH, insulin or FFA levels. Mean blood glucose levels were elevated significantly during spinal anaesthesia and surgery, but remained within the normal range.

Normal lactation and blood growth hormone studies

Plasma human growth hormone (HGH) was measured by a radioimmunoassay method both in a fasting resting state and during an insulin-induced hypoglycemic episode. There were 35 nonlactating control and 26 lactating nursing women tested in the late postpartum period. No statistically significant differences were demonstrated in either the blood glucose or plasma HGH levels. The significance of these findings is discussed in relation to the control of normal lactation and to the possible presence of a separate prolactin hormone in the human subject.

Metabolic clearance and production rates of human growth hormone.

The metabolic clearance rate (MCR) of human growth hormone (HGH) was determined by the constant infusion to equilibrium technique utilizing HGH-(125)I. 22 control subjects had a MCR of 229 +/-52 ml/min (mean +/-SD). No difference was evident between sexes, or between various age groups. Patients with acromegaly demonstrated normal MCR's. Moreover, acute elevations of plasma growth hormone concentrations in normal subjects did not alter the MCR of HGH. The MCR was relatively constant from day to day and within the day when subjects were evaluated in the supine position. In contrast, the assumption of the upright position was associated with a mean 24% decrease in the MCR. These results were contrasted with the MCR of HGH observed in a small number of patients with altered thyroid function or diabetes mellitus. In six patients with hypothyroidism the MCR (131 +/-36 ml/min) was significantly decreased (P < 0.001); whereas the MCR in eight patients with hyperthyroidism (240 +/-57 ml/min) did not differ from control subjects. The MCR in eight patients with insulin-independent diabetes mellitus (IID) (185 +/-41 ml/min) and in eight patients with insulin-dependent diabetes mellitus (IDD) (136 +/-31 ml/min) were significantly different from control subjects (P = < 0.05 and P = < 0.001, respectively). These data were interpreted to indicate that the plasma HGH-removing mechanism(s) is not saturated at physiologic plasma HGH levels, that plasma HGH levels alone may not permit distinction between variations in pituitary release of the hormone and its rate of clearance from the plasma, and that the estimation of the MCR of HGH may help clarify the mechanism of abnormal plasma HGH responses to various stimuli. Production rates of HGH (PR) in control subjects (347 +/-173 mmug/min) were contrasted with hyperthyroid patients (529 +/-242 mmug/min, P < 0.05), hypothyroid patients (160 +/-69 mmug/min, P < 0.02), IID (245 +/-100 mmug/min, NS), and IDD (363 +/-153 mmug/min, NS). Considerable variability in the determination of the concentrations of immunoprecipitable HGH-(125)I and endogenous plasma HGH concentrations was encountered at apparent equilibrium conditions. Since both factors are necessary for the PR calculations, the wide 95% confidence limits of the PR's did not permit a clear interpretation of the significance of these observations.

Plasma Human Growth Hormone Levels 4 Hours after Breakfast in Adolescent Twins and Adults

Plasma Human Growth Hormone (HGH) levels were determined in 176 healthy school children, 74 monozygotic and 14 dizygotic twins of 13-to 18-year-old, and in 34 healthy adult subjects 4 hrs. after the test breakfast. There was a considerable variation in plasma HGH concentrations, but most samples showed the values of 0.25mμg/ml to 40mμg/ml. The wide distribution of plasma HGH was especially noted in 13-and 14-year-old subjects in both sexes. In the male subjects, a definite difference in the distribution was noted between the 13-to 14-year-old school children and the 16-year-old or older subjects. In the female subjects, the difference was not so noticeable as in the male subjects. No correlation was noted between the plasma HGH levels and physical size of the subjects, nor between the values of plasma HGH in individual twins.