Failure

 Failure

By Peter Galvin, MD

Today’s topic is kidney, or renal, failure. More than 3.5 million people worldwide have kidney failure and must use dialysis or kidney transplantation to stay alive. But before we talk about kidney failure, let’s look at some kidney basics. Our kidneys have multiple roles in maintaining our health. They maintain acid-base and fluid balance, regulate sodium, potassium, and electrolyte balance, remove toxins, and regulate blood pressure. They also produce hormones like erythropoietin, which stimulates the bone marrow to produce red blood cells, and they activate vitamin D. The basic filtration unit in the kidney is the glomerulus. Each kidney contains millions of glomeruli. Kidney function is measured by calculating the glomerular filtration rate (GFR), which can either be directly measured by a 24-hour urine collection plus the serum blood urea nitrogen (BUN) and creatinine levels or calculated based on the serum BUN and creatinine. Creatinine is derived from the muscle protein creatine, so the more muscle mass a person has, the higher their creatinine will be. Normal serum creatinine is between 0.7 and 1.3, however a small, elderly woman may have kidney failure with a creatinine as low as 1.4.

GFR, as measured in mL/min/1.73 m2, is the highest at about age 2 and falls naturally throughout our lifetime. Men start out with rates between 100 – 130, women 90 – 120. Kidney failure can be caused by many factors and diseases, especially uncontrolled hypertension and diabetes. The decision to start dialysis is not based on lab values, for example a GFR of < 15, but upon factors caused by decreased kidney function. These factors include untreatable, or intractable, fluid overload, high potassium (hyperkalemia), and metabolic acidosis. Uremic factors, caused by high BUN (urea) levels, include uremic encephalopathy (brain dysfunction) and uremic pericarditis (inflammation of the heart lining). When efforts to counter these factors fail, dialysis must be initiated. Dialysis can be done two ways – via the blood (hemodialysis) which accounts for about 90% of dialysis cases, or peritoneal dialysis. Both methods require placement of access ports. Hemodialysis is usually done via an AV fistula (a direct connection between an artery and a vein), commonly placed in the arm. AV fistulas must be carefully protected as perforating one will cause rapid exsanguination and death. Peritoneal dialysis involves placing access ports in the abdomen.

Once dialysis has begun, a kidney transplant, if the patient qualifies, is paramount. This is because dialysis is fraught with danger. The 5-year survival rate for dialysis is less than 50%. Dialysis treatment-related complications are common and include vascular access dysfunction, infections, and hemodynamic instability during dialysis, and may cause distressing symptoms including cramping, post-dialysis fatigue, and poor quality of life. Cardiovascular complications, including heart attacks and strokes, are common and account for a sizeable chunk (40%) of the high dialysis mortality rate. In addition, complications of chronic kidney failure must be dealt with and include anemia (loss of erythropoietin causes the bone marrow to stop making red blood cells), hypertension, and bone mineral disorders. Dialysis does not treat these disorders.

The best way to treat chronic kidney failure is to prevent it from happening. This means controlling blood pressure and diabetes and avoiding nephrotoxic medications like injected opioids, overused NSAIDs like Motrin and ibuprofen, and certain antibiotics.

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