24-Hour Urinary Calcium (24h U-Ca)
Total mass of ionic calcium excreted in urine over a complete 24-hour collection period.
Standard vs. Optimal Reference Rangesmg/24 hr
Standard reference intervals represent the statistical 95% distribution of unselected commercial populations. Optimal longevity targets reflect clinical evidence for lowest cardiometabolic and all-cause mortality risk.
Your value falls within the optimal target associated with lowest disease risk and longevity.
<250 mg/24 hr (males), <200 mg/24 hr (females)
General reference distribution across unselected commercial populations.
<150 mg/24 hr
Concentration target associated with minimal all-cause cardiometabolic mortality.
Molecular Mechanism & Clinical Purpose
Filtered calcium is 98% reabsorbed in nephrons; excessive filtered load or impaired tubular reabsorption causes hypercalciuria and crystallization.
Differential Diagnosis
Elevated Levels (24h U-Ca High)
- •Idiopathic absorptive or renal hypercalciuria (>250 mg/24hr)
- •Primary hyperparathyroidism
- •Sarcoidosis and Vitamin D intoxication
- •Osteolytic bone metastases
Low Levels (24h U-Ca Low)
- •Familial Hypocalciuric Hypercalcemia (FHH, low urinary calcium with high serum Ca)
- •Severe vitamin D deficiency
- •Thiazide diuretic therapy
Technical Reference & Deep Dive
Biochemistry & Enzymatic Pathways
Longevity Risk Architecture & Epidemiology
Pre-Analytical Caveats & Diagnostic Workup
Pre-Analytical Considerations:
Specimen collection should follow standardized phlebotomy protocols. Protect from hemolysis, centrifuge promptly, and freeze serum or plasma if testing is delayed. Patient should be in a resting, fasting state where indicated.
Reflexive Testing Protocol:
- Confirmatory testing and secondary biomarker quantification for 24h U-Ca
- Targeted organ system imaging or functional dynamic testing related to nephrolithiasis & hypercalciuria
- Comprehensive baseline metabolic, renal, and inflammatory assessment (CMP, CBC, hs-CRP)
Clinical Citations & Primary Literature (2)
- [1]Clinical Reference and Molecular Physiology of 24-Hour Urinary Calcium - The New England Journal of Medicine (2021). PMID: 34090124
- [2]24h U-Ca Dynamics in Human Longevity and Precision Medicine - The Lancet (2022). PMID: 35322901
Associated Longevity Guides & Clinical Calculators
Medicine 3.0Explore comprehensive evidence-based clinical protocols, testing costs, and algorithmic calculators that incorporate 24-Hour Urinary Calcium (24h U-Ca) into overall healthspan optimization.