We present a patient on long-term hemodialysis (LTH) discovered to have a pheochromocytoma. A thorough workup pertaining his catecholamine status was performed, and intraoperative catecholamine changes were monitored. This condition poses some analytical difficulties as both interpretation of plasma catecholamine measurements and determination of their metabolic products are impaired. The literature about catecholamines with respect to hemodialysis is reviewed, and the known cases of pheochromocytoma in LTH patients are discussed. Predialysis norepinephrine concentrations were almost consistently elevated though less than 3-fold when compared to normal controls. Epinephrine is not significantly different in both groups. At least a 3.3-fold increase of epinephrine or norepinephrine in LTH patients with adrenal pheochromocytomas is observed. We conclude that plasma epinephrine elevations can be evaluated in the conventional manner, and norepinephrine concentrations beyond a 3-fold elevation should raise the suspicion of a pathological catechol excess syndrome. The interpretation of plasma homovanillic acid and vanillylmandelic acid in this condition is complicated by the lack of data in LTH patients without pheochromocytoma. Markedly elevated baseline concentrations for these parameters are assumed.

AN attenuated catecholamine secretion seems not to be the putative mechanism of a reduced awareness of human insulin-induced hypoglycemia.

Although pituitary hormones play only a minor role in acute hormonal counterregulation during insulin-induced hypoglycemia, their concomitant secretion with the profound sympathoadrenal response provides an indicator of hypothalamic-pituitary activation. The release of different amounts of beta-endorphin, growth hormone, and adrenocorticotropin during human (HI) and porcine (PI) insulin-induced hypoglycemia would serve as a pointer to a different insulin species effect on hypothalamic-pituitary response. We performed a controlled, double-blind study with randomization to either HI or PI to compare insulin effects during developing and established hypoglycemia. The glucose clamp technique was used to lower the blood glucose concentration stepwise (3.3, 2.2, 1.7 mmol/l) over similar periods in ten patients with insulin-dependent diabetes mellitus. beta-endorphin, growth hormone, and adrenocorticotropin levels were determined by radioimmunoassay from arterialized blood at the above plateaus. A different action of HI or PI on peripheral glucose metabolism was not found. Pituitary hormones increased significantly during hypoglycemia (analysis of variance for hypoglycemic effects: beta-endorphin, P < 0.02; growth hormone, P < 0.04; adrenocorticotropin, P < 0.05). No insulin species effect was detected. Hypothalamic-pituitary activation during insulin-induced hypoglycemia is independent of the insulin species used, which supports earlier observations of an identical sympathoadrenal response during HI- and PI-induced hypoglycemia.

Circadian rhythm ofparathyrin and Calcitonin concentrations in serumSummary: The cireadian variations of serum intact parathyrin, C-terminal parathyrin (65 -84), mid-region parathyrin (44 -68) fragments, calcitonin, total calcium, ionized calcium, albumin and phosphate were measured in five healthy subjects. Intact parathyrin, parathyrin (44 -68) and calcitonin show a synchronous diurnal fluctuatipn with a noctufnal increase to a maximum between 24.00 and 2.00 hours. Whereas phosphate has a marked circadian rhythmicity with a zenith between 1.00 and 8.00 hours, total calcium and albumin show a tendency to decrease between 20.00 and 6.00 hours. Ionized calcium concentration remains constant over the whole day.

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