Calcium supplementation increases blood creatinine concentration in a randomized controlled trial

Area of Science:

• Gerontology and Nutritional Science
• Nephrology and Clinical Biochemistry

Background:

• Calcium supplements are commonly used by older adults for bone health.
• The impact of calcium on kidney function, specifically creatinine levels, remains understudied.

Purpose of the Study:

• To investigate the effect of daily calcium supplementation on blood creatinine concentrations.
• To assess potential correlations with alcohol consumption and baseline kidney function.

Main Methods:

• A randomized controlled trial involving 1,675 healthy participants aged 45-75 with a history of colorectal adenoma.
• Participants received daily calcium (1200 mg), vitamin D3 (1000 IU), both, or placebo for 3-5 years.
• Blood creatinine and total calcium levels were measured after one year, with analysis using multiple linear regression.

Main Results:

• Calcium supplementation led to a small, statistically significant increase in blood creatinine levels (0.013±0.006 mg/dL) after one year.
• The increase in creatinine was more pronounced in participants with higher alcohol consumption or lower baseline estimated glomerular filtration rate (eGFR < 60 ml/min/1.73 m2).
• The effect was partially mediated by increased blood total calcium and was independent of vitamin D supplementation; no further creatinine increase was observed after the first year.

Conclusions:

• Daily 1200 mg elemental calcium supplementation caused a minor elevation in blood creatinine in healthy adults.
• These findings suggest potential clinical implications for monitoring kidney function in individuals taking calcium supplements, especially those with risk factors.