Abstract. Effects of a 72-h prostacyclin (PGI2) infusion (5 ng/kg/min) on hormone levels were studied in 11 patients (5 males, 6 females) suffering from obliterative arterial disease of the lower extremities. ACTH, cortisol, TSH, prolactin (Prl), GH, LH, FSH, T3, T4, calcitonin, parathyroid hormone (PTH), insulin, plasma renin activity (PRA), aldosterone and testosterone levels were measured at −15, 0, 30, 120, 240 min and 24, 48, 72 and 96 h after the infusion. During the first 240 min Prl and GH levels showed an increase that was thought to be either an effect of release of hormones or a consequence of stress. At the same time the thyroid hormones, T3, T4 and calcitonin decreased, presumably owing to an alteration in the blood flow to the thyroid gland. All these hormone levels returned to normal at 24 h in spite of the infusion continuing. PRA increased only during the second half of the infusion. No changes were found in the levels of ACTH, cortisol, TSH, LH, FSH, PTH, insulin, aldosterone and testosterone during the infusion. Five diabetics showed the same hormonal changes as the non-diabetics and their blood sugar levels remained unaffected during and after the procedure.
G. Irsy, Gy. Blaskó, M. Góth, I. Szabolcs, B. Gachályi, and G. Szilágyi
L Kovacs, MI Goth, I Szabolcs, O Dohan, A Ferencz, and G Szilagyi
OBJECTIVE: To evaluate the renin-aldosterone system and insulin secretion in hyperparathyroidism and their effects on blood pressure regulation. DESIGN: Studies were carried out on patients with primary hyperparathyroidism (PHPT) prior to and following removal of the parathyroid tumor. METHODS: Sixteen normotensive and euglycemic patients with PHPT were studied. The following parameters were measured: basal and stimulated plasma renin activity (PRA) and aldosterone (ALD) secretion: parathormone (PTH) and serum electrolytes. Insulin and glucose levels were measured during an oral glucose tolerance test. RESULTS: Systolic but not diastolic blood pressure showed a decrease following surgery, from 123.3+/-13.0/80+/-8.6 to 116.7+/-13.5/77.3+/-8.8 mmHg. The decrease in the systolic pressure was not clinically significant. After surgery, both the basal and stimulated PRA and ALD values decreased, and the preoperative pathological values returned to normal: PRA basal: 1.79 --> 0.70 ng/ml/h, P=0.0049; PRA stimulated: 7.76 --> 1.90 ng/ml/h, P=0.0031; ALD basal: 111.5 --> 73.0 pg/ml, P=0.0258; ALD stimulated: 392.5 --> 236.0 pg/ml, P=0.0157. The postoperative decrease in the PRA correlated with the changes in PTH levels (r=0.5442, P < 0.05, n=16) but did not correlate with the changes in serum calcium concentrations. Both the fasting and stimulated insulin levels decreased after surgery but remained within the normal range: insulin fasting: 10.2 --> 5.0 mIU/l, P=0.0218; insulin area under the curve: 5555 --> 3296 mIU/l*min, P=0.0218. There was no correlation between the changes in insulin levels and PTH or ion levels. Sodium, potassium and blood glucose levels remained unaffected by parathyroid surgery. CONCLUSIONS: In a population of normotensive hyperparathyroid patients an increased activity of the renin-aldosterone system related to PTH was found and surgery resulted in a small and insignificant decrease in blood pressure. This change was accompanied by a significant decrease in the activity of the renin-aldosterone system indicating the role of the renin-aldosterone system in the regulation of blood pressure in PHPT. Both fasting and stimulated insulin values decreased following removal of the parathyroid tumor, but with no individual correlation with PTH and calcium levels.
G Brabant, P Beck-Peccoz, B Jarzab, P Laurberg, J Orgiazzi, I Szabolcs, A P Weetman, and W M Wiersinga
Mild forms of hypothyroidism – subclinical hypothyroidism – have recently been discussed as being a risk factor for the development of overt thyroid dysfunction and for a number of clinical disorders. The diagnosis critically depends on the definition of the upper normal limit of serum TSH as, by definition, free thyroxine serum concentrations are normal. Cut-off levels of 4–5 mU TSH/l have been conventionally used to diagnose an elevated TSH serum concentration. Recent data from large population studies have suggested a much lower TSH cut-off with an upper limit of 2–2.5 mU/l but application of strict criteria for inclusion of subjects from the general population studies aiming at assessing TSH reference intervals (no personal or family history of thyroid disease, no thyroid antibodies and a normal thyroid on ultrasonography) did not result in an unequivocal upper limit of normal TSH at 2.0–2.5 mU/l. When summarizing the available evidence for lowered upper TSH cut-off values and their potential therapeutic implications there is presently insufficient justification to lower the upper normal limit of TSH and, for practical purposes, it is still recommended to maintain the TSH reference interval of 0.4–4.0 mU/l. Classifying subjects with a TSH value between 2 and 4 mU/l as abnormal, as well as intervening with thyroxine treatment in such subjects, is probably doing more harm than good.