Foot Health

Kidney disease and the feet

Chronic kidney disease, also called end stage renal failure, describes the gradual loss of kidney function. The kidneys filter waste and excess fluids from the blood, which is then excreted in the urine. When chronic kidney disease reaches an advanced stage, dangerous levels of fluid, electrolytes and wastes can build up in the body. This affects all parts of the body.

Diabetes is the commonest cause of renal disease resulting in the Western world accounting for 20 to 44 percent of renal replacement therapy. In 2018 in The Bahamas there were more than 600 people on dialysis. This number has increased in the past three years. Just as many males and females are on dialysis. The reasons why people are on dialysis include hypertension (25.6 percent), diabetes mellitus (28.0 percent) and chronic glomerulonephritis (13.3 percent).

There is a much higher chance of diabetic foot disease in those people with renal disease and the outcomes, including amputations and death, are also much higher. This increase in foot disease is seen across all categories of kidney disease including chronic kidney disease (CKD) stages three and four, those on hemodialysis, peritoneal dialysis, kidney transplant as well as pancreas and kidney transplant. Three major diabetic foot conditions that kidney failure tend to make worse are ulcerations, Charcot foot and necrotic toes, which can all result in amputations.

Diabetic foot disease increases as renal function decreases. As the glomerular filtration rate (eGFR – a test of kidney function) decreases the chances of diabetic foot ulcers and lower extremity amputations increase. Starting hemodialysis can increase the incidence of foot ulcers that may be related to the reduction in the oxygen supply to the feet. Dialysis is an independent predictor (61 percent) of foot ulcers in those with diabetes in addition to the peripheral neuropathy, infection and peripheral vascular disease. Twenty two percent of people with diabetes and a kidney transplant underwent amputation for foot ulceration. Of those that had pancreas and kidney transplant, 18 percent had lower extremity amputation and 12 percent had Charcot foot disease. In one study, 82 percent of subjects presenting to a multidisciplinary foot clinic with necrotic toes had endstage renal disease.

Foot conditions that may be seen in patients with diabetes and kidney disease.

Peripheral neuropathy: The same microvascular disease process in diabetes that causes nephropathy (kidney disease) also causes peripheral neuropathy, the major cause for diabetic foot disease. Almost all people with endstage renal failure due to diabetic nephropathy will also have peripheral neuropathy. The worse the nephropathy (kidney disease) the worse the peripheral neuropathy (diabetic nerve).

The exact reason kidney disease patients tend to develop neuropathy is not clearly known, but the following are some possible reasons:

• The deficiencies of essential nutrients like thiamine (vitamin B1) or an excess of zinc might damage the nerve and contribute to neuropathy.

• Hyperparathyroidism (excess production of parathyroid hormone), has also been blamed.

• The dialysis access (fistula or graft) in hemodialysis patients can lead to carpal tunnel syndrome like symptoms in the arm with the port or decrease blood flow to the area.

• Blood may go into the surrounding tissues and can compress a nerve.

• Patients with high phosphorus levels can see calcium phosphate deposits which could contribute to neuropathy.

• Inadequate dialysis can also lead to build up of toxins in the blood and lead to neuropathy.

Peripheral vascular disease: Both diabetes and renal disease have been shown to contribute to higher levels of peripheral vascular disease. Calcification leading to hardening of the arteries can lead to low blood flow to the feet. This can lead to the necrotic (gangrene) toe and poor wound healing.

Increased risk of foot infection: Uremia is when there are toxins in the blood before dialysis. This can decrease the immune system functioning and decrease its ability to defend against infection. A greater proportion of foot ulcers will be infected and a greater proportion will have deep seated infection such as osteomyelitis.

Dialysis therapy itself has been shown to be an independent predictor of foot ulceration in people with diabetes in addition to neuropathy and peripheral vascular disease. Anemia (low blood cell count) is also common in person on dialysis which leads to poor tissue oxygen and delayed wound healing.

Reduced ability to perform foot self-care or foot inspection can lead to foot complications. The same damage to blood vessels that causes peripheral neuropathy and kidney disease also damages the eyes causing blindness and the tendons and ligaments causing decrease dexterity and flexibility. Hemodialysis three times weekly may also result in patients neglecting foot care.

Depression is often seen in patients on dialysis which can affect how they follow their treatment plan, attend clinic and perform self-care such as foot care.

If you have kidney disease and or have any concerns about your feet, see a podiatrist to have a full evaluation.

• For more information on foot conditions, visit www.apma.org, healthcentral.com, or email us at foothealth242@gmail.com. To see a podiatrist, visit Bahamas Foot Centre, Rosetta Street, or telephone 325-2996 for an appointment at Bahamas Surgical Associates Centre, Hilltop Medical, or call 394-5820 for an appointment. You can also visit Lucayan Medical Centre in Freeport, Grand Bahama, or telephone 373-7400 for an appointment.

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