Kidneys & Your Skin: No Kidding

The kidneys perform several important jobs such as rid your body of waste products, balance the volume of fluid in the body, change blood pressure, make red blood cells and produce active vitamin D. Many people with kidney disease are managed and maintained by hemodialysis, but this often does not fully compensate. As a result, significant dysfunction in the metabolic system occur such as anemia, altered calcium-phosphate function, hyperparathyroidism and glucose intolerance. These altered functions cause uremia and ultimately impact various organ functions. A uremic condition happens when the kidneys become compromised and the toxins that the kidneys normally send out through the urine end up in your bloodstream.

Skin and nail changes in the presence of kidney disease are commonly encountered and can be due to the cause of the underlying kidney disease, as a result of uremia or therapies that lower the immune system. The following are some of the skin and nail findings in people who have kidney disease.

1. Calcinosis Cutis: This results from calcification of the skin as a result of issues with an elevated calcium/phosphate ratio. There are different types such as a localized calcinosis or a systemic variety called metastatic calcinosis cutis. When the condition is systemic, normalization of calcium and phosphate ratios may regress lesions.
2. Calciphylaxis: Between 1-4% of hemodialysis patients develop this painful condition. As a result of toxins that build up in the blood, vessels become damaged and cause tissue death or necrosis. People who are female, have diabetes, use calcium-phosphate binders, take vitamin D, are obese or immunosuppressed, take systemic corticosteroids, or have a hypercoagulable state (increased tendency for blood clots), have a higher risk for this condition and inevitably have higher mortality and morbidity rates.
3. Kyrle Disease: Between 4-10% of dialysis patients develop this condition where the dermis of the skin pushes through the upper layer called the epidermis and a plug of keratin is characteristic of the lesions. Often associated with end stage renal disease (ESRD) and/or diabetes, this cause exactly is unknown. Therapeutic options have variable success.
4. Lindsay’s Nails: Also called half-and-half nails, are seen in approximately 40% of patients on dialysis and disappear after kidney transplantation. A white color is seen closer to the cuticle and a red to brown color is seen distally. Other nail changes such as Beau’s lines, onycholysis and vessel abnormalities near the nailfold may occur. Beau’s lines are horizonal or transverse lines in the nails. Onycholysis is where the nail separates from the nailbed.
5. Nephrogenic Systemic Fibrosis: This occurs in individuals with kidney disease who have been exposed to a contrast agent used in diagnostic studies such as gadolinium. In this disorder, skin becomes fibrotic and may affect skeletal muscle, the diaphragm, lymph nodes, heart, lungs, pleura, liver, thyroid, and genitourinary tract.
6. Bullous Disease: Blistering disorders such as porphyria cutanea tarda (PCT) and pseudoporphyria are poorly understood in patients on hemodialysis, but is likely multifactorial. Porphyrins in the blood may not be fully dialized, elevated iron in the blood from increased blood transfusions, medications and an increased incidence of hepatitis C may contribute.
7. Uremic Frost: This phenomenon is less frequent with the availability of dialysis, but may occur in individuals who suffer from an elevated blood urea nitrogen (BUN). Urea concentrates in the sweat and is deposited on the skin after evaporation. Crystals are visible on the skin, especially on the face, neck or trunk. Elevated urea levels may also cause a yellowish hue to the skin as well.
8. Xerosis and Pruritus: Xerosis is dry skin and between 50-90% of patients on dialysis suffer from this. This may occur from a reduction in sweat, elevated vitamin A levels or shrinkage of sebaceous glands. However, vitamin levels in the majority of dialysis patients are normal. Pruritus is another name for itching. Itching in patients with ESRD can be persistant and aggravating. Between 50-90% of patients on dialysis experience this. Attributable causes may occur as a result of the xerosis.

Reference
Callen JP, Jorizzo JL. Renal disease and the skin. In: Maiberger MP, Nunley JR, eds. Dermatological Signs of Systemic Disease. 5th ed. China: Elsevier; 2017: 323-329.