POTASSIUM CAUSES CALCIUM RETENTION IN HEALTHY-ADULTS

The administration of 60 mmol/d of KHCO3 to healthy adults reduced uri nary calcium excretion by 0.9 mmol/d and caused calcium balance to bec ome equivalently more positive. Other studies showed that 90 mmol/d of KHCO3 reduced both daily and fasting urinary calcium excretion rates, whereas deprivation of either KCl or KHCO3, using synthetic diets, wa s accompanied by increased daily and fasting urinary calcium excretion rates. A significant inverse relationship between the changes in urin ary calcium and the changes in urinary potassium was observed: DELTA u rinary Ca (mmol/d) = 0.29 - 0.015 DELTA urinary K (mmol/d); r = -0.65. Correlative evaluation of additional data suggested that the fall in urinary calcium during potassium administration may be related to the natriuretic effects of potassium, resulting in ECF-volume contraction or to potassium-induced phosphate retention and suppression of calcitr iol synthesis, or to both mechanisms.