This graph shows the association between 24-hour urine calcium (mg/day) excretion and the likelihood of being a kidney stone former. The data come from 3 prospective cohort studies:
- Nurses' Health Study (NHS) – All female
- Nurses' Health Study II (NHS II) – All female (younger than those in NHS I)
- Health Professionals Follow-Up Study (HPFS) – All male
The analyses are based on values from 2237 cases with a history of kidney stones and 1113 controls who did not have a history of kidney stones. The arrows show the traditional cutoff points for elevated urine calcium (250 mg/day in females and 300 mg/day in males). Note that the risk is already substantially increased below these cutoffs, emphasizing that the risk should be viewed continuously rather than dichotomously.
Reproduced with permission from Gary Curhan, MD, ScD.
