The body normally keeps serum and intracellular calcium levels under tight control through bone resorption and urinary excretion. The reference range for urine calcium is as follows: Males: 25-300 mg/24-hour specimen*. Females: 20-275 mg/24-hour specimen*. Hypercalciuria: >350 mg/24-hour specimen. *These levels are reflective of individuals with average calcium intake, which is 600-800 mg/day.