Effects of a typical acute oral calcium load on arterial properties and endothelial function in healthy subjects.

BACKGROUND/OBJECTIVES: Often recommended, calcium supplements have been incriminated as increasing the risk of cardiovascular events, whereas dietary calcium has generally been exonerated. As a first step to address the vascular safety of such dietary measures at the clinical nutritionist toolbox, we sought to determine and compare the acute effects of a typical oral calcium load, provided either as a supplement or as food, on vascular parameters assessed noninvasively in healthy subjects. SUBJECTS/METHODS: In this acute, cross-over, random-order intervention, 11 young and healthy vitamin D-sufficient volunteers (8 women/3 men, 33±6.1 years, body mass index 22.6±2.3 kg/m(2)), ingested 600 mg of calcium twice, once as calcium citrate and the other time from dairy products. Biochemical, vascular and hemodynamic parameters, before and 2 h after each challenge, were compared. Arterial stiffness was studied by measuring pulse wave velocity, augmentation index and large (C1) and small (C2) arterial compliance. Endothelial function was assessed by flow-mediated dilation (FMD). RESULTS: Despite effective calcium loading accompanied by a significant 60% parathyroid hormone level reduction on both occasions, there were no clinically significant changes in the vascular parameters neither in comparison with baseline, nor between the studies. A decrease in heart rate with no change in cardiac output was noticed after the supplement. CONCLUSIONS: An effective calcium load has no clinically significant untoward effect on the vascular properties of young healthy subjects, regardless of its source. Additional studies should determine whether this holds true for chronic calcium supplementation, particularly in subjects with a priori vascular impairment.

Hypothalamic-pituitary function in patients with prolonged coma.

In eight patients (six males and two females) hospitalized for prolonged coma (164-1320 days; five patients were in traumatic coma, two after cardiac arrest during surgery, and one after a venomous scorpion sting), diurnal variation of cortisol secretion, human (L) GH, PRL, TSH secretion as well as the release of the pituitary hormones after TRH and L-dopa stimulation were assessed. Serum T4 cortisol, hGH, hPRL, and hTSH levels were normal. The cortisol diurnal variation was preserved in six patients. In seven of eight patients, the hPRL and hTSH responses to TRH test were normal and in five patients, there was a rise of more than 150% in serum hGH concentrations. After L-dopa administration, five patients responded with a rise in hGH. In three patients, there was no response of hGH to TRH or L-dopa. Five patients responded with significant reduction in the serum hPRL concentration after L-dopa, and in three patients, no change was observed. It was concluded that patients with prolonged coma have variable hypothalamic pituitary function. They preserve the cortisol diurnal variation and the hypothalamic-pituitary-thyroid axis as well as PRL secretion; however, hGH secretion may respond abnormally to various stimuli.

Renal glomerular and tubular function following acute insulin deprivation in juvenile diabetes mellitus.

The effects of acute deprivation of insulin on renal glomerular and tubular functions were studied in 10 children with juvenile diabetes mellitus. Serum glucose concentrations were similar when insulin was administered (251 +/- 112 mg/dl) and when it was withheld (306 +/- 130 mg/dl; 0.5 greater than 0.2). Acute insulin deprivation was associated with a significant reduction in glomerular filtration rate, from 151 +/- 48 ml/min/1.73 m2 to 114 +/- 41 ml/min/1.73 m2 (p less than 0.01). The fractional excretion of sodium rose from 0.45 +/- 0.43 to 0.85 +/- 0.54% (p less than 0.05) and was associated with an enhanced natriuresis; the urinary excretion of sodium increased from 1.67 +/- 1.23 to 2.43 +/- 1.72 microEq/min/kg body weight (p less than 0.05), whereas the urinary excretion of phosphate was not significantly altered from control values. During insulin deprivation a drop occurred in the serum concentration of calcium from 10.37 +/- 0.52 to 9.73 +/- 0.61 mg/dl (p less than 0.01) as well as in its urinary excretion from 0.34 +/- 0.24 to 0.24 +/- 0.20 microgram/min/kg body weight (p less than 0.01). The serum concentration of potassium rose from 4.44 +/- 0.41 to 4.96 +/- 0.51 mEq/l, but its urinary excretion was not significantly different from control values. These data suggest that in juvenile diabetes mellitus the acute deprivation of insulin, dissociated from fluctuations in serum glucose concentration, is associated with a fall in glomerular filtration rate, an increased natriuresis, and a modified calcium and potassium homeostasis.

Hyperuricosuria in cystic fibrosis patients treated with pancreatic enzyme supplements. A study of 16 patients in Israel.

Uric acid metabolism was evaluated in 16 Israeli cystic fibrosis patients, all of whom were taking pancreatic enzyme supplements. The findings were compared with those in a recent study of uric acid metabolism in 65 healthy Israeli children. Hyperuricemia of 4.9 +/- 0.2 (SE) mg/dl was found in the cystic fibrosis patients, compared with a normal level of 3.1 +/- 0.2 mg/dl ( P < 0.05). In five patients, 24-h urine collections were assayed and all showed hyperuricosuria. Thirteen patients had high urinary uric acid/creatinine ratios. Hyperuricosuria increased with the age of the patient and when the administered dosage of pancreatic enzyme exceeded 10,000 lipase units/kg body weight. Despite normal levels of serum creatinine and urea, and normal creatinine clearance in the cystic fibrosis patients, risk of future renal damage seems obvious and preventive measures should be considered.

Congenital hypoaldosteronism. Thirteen year follow-up in identical twins.

Identical male twins suffering from congenital hypoaldosteronism due to a rare adrenal enzyme deficiency between corticosterone and aldosterone were followed-upfrom birth till their present age of 13 years. The symptoms of salt loss disappeared and normal growth rate resumed following treatment with DOCA and salt supplementation. Discontinuation of mineralocorticoid administration at the age of 7 years resulted during a 5-year period in a marked decline in their growth rate. Labororatory data revealed a persistent, albeit less pronounced, metabolic impairment. Mineralocorticoid administration was resumed and the twins entered normal puberty and increased their growth rate, emphasizing their need for continued mineralocorticoid administration to maintain adequate growth rate and development.