The synergistic interaction of
fructose and
magnesium (Mg) deficiency on kidney calcification was compared in male and female rats. Male and female weanling rats were divided into four dietary groups:
fructose or
starch, with or without Mg. Rats were fed their respective diets for 9 weeks, and 24 h urine was collected to measure urinary output, pH, Mg,
calcium (Ca), and
oxalic acid. Rats were fasted overnight. After
decapitation, blood was collected immediately, and kidneys were removed to determine their Mg and Ca content. Dietary
fructose significantly increased kidney Ca in female rats fed deficient or adequate Mg diet and in male rats fed Mg-deficient diet only; the greatest kidney calcification occurred in female rats fed Mg-deficient diet (P less than 0.0001). Even in
starch groups female rats fed the Mg-deficient diet showed some kidney Ca accumulation. The synergistic interaction of
fructose and
magnesium deficiency on
nephrocalcinosis was significantly greater in female than in male rats. Low urinary output, optimal pH 6.8 for
calcium phosphate precipitation, hypercalcaemia,
hypercalciuria, hypomagnesuria, and low ratio of urinary Mg to Ca may independently or multifactorially contribute to
nephrocalcinosis. The possible mechanism of this interaction is discussed.