What vitamin deficiencies can cause nail deformities in patients undergoing peritoneal dialysis?

Vitamin Deficiencies Causing Nail Deformities in Peritoneal Dialysis Patients

Biotin deficiency is the primary vitamin deficiency that directly causes nail deformities (specifically brittle nails/onychoschisis) in peritoneal dialysis patients, though this is rare; more commonly, iron deficiency (often accompanied by B-vitamin deficiencies) contributes to nail abnormalities in this population.

Direct Nail-Related Vitamin Deficiencies

Biotin (Vitamin B7)

• Biotin deficiency directly causes brittle nails (onychoschisis) and hair loss, and supplementation has proven successful in treating nail brittleness 1
• Genetic abnormalities or malabsorption (such as excessive raw egg consumption containing avidin) can result in biotin deficiency 1
• While biotin deficiency is rare, peritoneal dialysis patients may be at increased risk due to dietary restrictions and potential losses 1

B-Complex Vitamins with Nail Manifestations

Vitamin B6 (Pyridoxine):

• Deficiency causes dermatitis, cheilosis, and peripheral neuritis, which can indirectly affect nail health 1
• 67% of pediatric dialysis patients and 26 of 30 children receiving dialysis consumed less than the RDA for vitamin B6 2
• The KDOQI guidelines recommend 10 mg pyridoxine-HCl daily for adult hemodialysis and peritoneal dialysis patients to correct documented deficiency 2

Vitamin B2 (Riboflavin):

• Deficiency causes cheilosis, glossitis, and poor growth 1
• Conflicting reports exist about riboflavin levels in peritoneal dialysis patients, though some authors recommend supplementation 3

Vitamin B12 (Cobalamin):

• While not directly causing nail deformities, B12 deficiency should be evaluated in peritoneal dialysis patients with persistent anemia or other manifestations 1
• The National Kidney Foundation recommends 0.5 mg vitamin B12 daily for dialysis patients 4
• Use methylcobalamin or hydroxocobalamin instead of cyanocobalamin in renal dysfunction, as cyanocobalamin requires renal clearance of cyanide which may accumulate 4

Indirect Contributors to Nail Abnormalities

Iron Deficiency

• Iron deficiency is extremely common in peritoneal dialysis patients and causes nail abnormalities including koilonychia (spoon nails) 1
• Urinary losses of transferrin and iron occur in nephrotic-range proteinuria 1
• Iron deficiency should be monitored and treated before attributing nail changes solely to vitamin deficiencies 1

Copper Deficiency

• Copper deficiency can contribute to anemia and should be evaluated in peritoneal dialysis patients with persistent symptoms after iron and erythropoietin therapy 1
• Copper functions with zinc in superoxide dismutase, an antioxidant enzyme 1

Vitamin D Deficiency

• 97% of peritoneal dialysis patients have vitamin D deficiency (<15 ng/mL), with 86% having undetectable levels 5
• Vitamin D deficiency causes bone pain and muscle weakness, which may indirectly affect nail health through overall nutritional status 5
• Ergocalciferol 50,000 IU orally once weekly for 4 weeks corrects deficiency safely without affecting calcium, phosphorus, or PTH levels 5

Practical Supplementation Approach for Peritoneal Dialysis Patients

Water-Soluble Vitamins

• Most peritoneal dialysis patients have intakes of water-soluble vitamins lower than the RDA, with significantly lower intakes in those with reduced residual renal function 6
• Little thiamin is lost through the peritoneal route, but vitamin B1 deficiency is most frequently found in CAPD patients due to increased requirement from high glucose intake in dialysis solution 1, 3
• Supplementation with thiamine, riboflavin, pyridoxine, pantothenic acid, niacin, and ascorbic acid in one multivitamin preparation (without vitamin A) plus folic acid after each dialysis is recommended 7

Critical Monitoring Points

• Assess residual renal function and urea clearance, as these independently predict micronutrient intakes 6
• Patients with good dietary intake or those receiving specialized renal formulas may already meet vitamin requirements 2
• Monitor for medication interactions that interfere with pyridoxine and folate metabolism 2

Common Pitfalls to Avoid

• Do not use vitamin A supplementation in dialysis patients, as there is no need and potential for toxicity 7
• Avoid cyanocobalamin in favor of methylcobalamin or hydroxocobalamin to prevent cyanide accumulation 4
• Do not assume nail deformities are solely vitamin-related without evaluating iron, copper, and overall nutritional status 1
• Peritoneal dialysis patients with low residual renal function require more aggressive supplementation due to reduced overall food intake 6