Chronic kidney disease (CKD), also known as renal disease, is a condition in which the kidneys lose function and fail to work properly over time. This can have a severe effect on health and quality of life, and can result in high blood pressure, nerve damage, weak bones, anemia and eventually, kidney failure, dialysis, kidney transplantation and early death.
Anemia, one common condition associated with CKD, is characterized by very low hemoglobin and red blood cell count in the blood. Untreated, anemia can lead to separate clinical symptoms, apart from those related to CKD. Symptoms may include fatigue, skin pallor, shortness of breath, lightheadedness, dizziness, or a fast heartbeat. Evidence has been presented to support vitamin D’s relationship with anemia. Research has shown that vitamin D status and anemia are inversely related, and further studies have identified an association between vitamin D and anemia in CKD patients who have yet to undergo dialysis. These clinical implications led researchers from this study to hypothesize that vitamin D may play a role in anemia that is associated with end-stage renal disease (ESRD).
This cross sectional study included 410 patients from an ethnically homogeneous Korean population who had undergone renal transplant (RTx) due to progression of CKD, were between the ages of 18-70 years old and had serum 25(OH)D3 concentrations measured before RTx procedures. The participants were placed in to two groups; group 1 had vitamin D levels <10 ng/ml, while group 2 had vitamin D levels of >10 ng/ml.
The researchers analyzed serum 25(OH)D levels and hemoglobin (Hg) concentrations, a marker for anemia, from the 410 ESRD patients, and this is what they found:
- None of the participants had vitamin D levels within the sufficient range (>30 ng/ml).
- The overall mean serum 25(OH)D3 concentration was 11.1±6.4 ng/mL, while the mean 25(OH)D3 level was 6.5±1.8 ng/mL in group 1 and 17.2±5.6 ng/mL in group 2.
- Pearson’s correlation analysis revealed a significant correlation between 25(OH)D3 and Hg levels (p<0.001).
- Logistic regression analysis revealed that patients in group 1 had a significantly higher risk for developing anemia than group 2 patients, even after adjusting for confounding factors (OR=3.857, p=0.036).
The researchers concluded:
“In this study, we demonstrated that patients with 25(OH)D3 levels <10 ng/dL had a higher risk of developing anemia than patients with 25(OH)D3 levels ≥10 ng/dL.”
“This association remained significant even after adjusting for potentially important risk factors for anemia.”
In patients with ESRD, anemia can cause a multitude of dangerous outcomes, including, but not limited to, cardiovascular consequences and mortality. Vitamin D could potentially be an important modifiable risk factor for anemia in ESRD patients. In addition to their conclusions, the researchers acknowledged a few key limitations to this study. First, all participants came from a homogeneous Korean population, so the results may not be generalized to other populations. Second, serum 25(OH)D concentrations were only measured prior to RTx, so the researchers were unable to determine the effect of a potentially changing serum 25(OH)D level on Hg concentration. Last, this study had a cross sectional design, which limits the strength of the findings.
In order to prove a causal relationship between vitamin D deficiency and anemia in ESRD patients, randomized controlled trials are needed.
Peterson, R. & Cannell, JJ. End-stage renal disease patients with vitamin D deficiency may be at increased risk of anemia. The Vitamin D Council Blog & Newsletter, 2016.