This study indicates that the bone mineral density of the lumbar spine, femoral neck and the midshaft of the radius are not significantly decreased in premenopausal patients with endogenous subclinical hyperthyroidism resulting from a solitary autonomously functioning thyroid nodule. Conversely, findings hint at the possibility that long-lasting endogenous subclinical hyperthyroidism may be a contributing factor to the development of osteoporosis in some post-menopausal women, mostly at sites where cortical bone preponderates.

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Simultaneous measurement of plasma renin activity (PRA), plasma aldosterone concentration (PA) and urinary aldosterone excretion (UAE) was made using the RIA method along with determination of Na and K balance in 1-week-old neonates with gestational age of 30–41 weeks (mean 35.9 weeks) and birth weight of 1,160–4,670 g (mean 2,680 g). It was demonstrated that PRA decreased from the value of 36.3 ± 6.3 ng/ml/h (mean ± SE) to a level of 10.2 ± 2.1 ng/ml/h (p < 0.001), PA did not change and UAE increased from 3.3 ± 0.8 to 7.8 ± 1.4 μg/day (p < 0.01) as the gestational age advanced from 30–32 to 39–41 weeks. There was no correlation between either PRA and PA or PA and UAE. PRA showed a significant positive correlation with urinary Na excretion (p < 0.001) and plasma K concentration (p < 0.05), but it was negatively related to Na balance (p < 0.001). Significant negative correlations were found between UAE and urinary Na excretion (p < 0.05), urinary Na/K ratio (p < 0.01) and plasma K concentration (p < 0.05); however, UAE positively correlated with Na balance (p < 0.01). It is concluded that, in response to renal salt wasting and to the subsequent negative salt balance, premature infants can augment their PRA above values found for full-term infants. Their adrenals, however, failed to respond adequately to this stimulation.

Using ⁸⁵Sr-labelled microspheres as nonabsorbable markers, the effect of age on gastrointestinal propulsion motility was determined in conscious rats. There was no significant correlation between the gastric emptying rate or the propulsion motility of the small intestine and the age of the rats. However, the transit time of the intestinal content in the caecum in adult (17- to 20-month-old) rats was about fivefold the value found in weanling (19-day-old) rats. Also the transit time of the large intestine was found to be prolonged by about 70 % during the life span investigated.

No abstract