Fly Well

My favorite pie

March 1, 2012

For many, “England” and “fantastic food” should never appear in the same sentence. As a native, I dispute this egregious mischaracterization—there’s darn good nosh to be had in the land of my birth. Granted, steak and kidney pie isn’t to everyone’s liking, but I am a fan and encourage you to sample this delicacy. It tastes great and will provide new respect for humble kidneys, whether wrapped in pastry or not. As more than 10 percent of Americans harbor kidney disease, please read on about this crafty killer.

SackierShaped like large kidney beans—no surprise—and fist-size like the heart (or fist), approximately four and one-half inches long and weighing five and one-half ounces, our kidneys sit behind the belly, on either side of the spine, the right a bit lower, the left closer to the midline. Each has a big artery delivering blood and a large vein taking it away, while a conduit—the ureter—carries urine to the bladder. Inside, 1 million filtration units, nephrons, each consisting of a tangle of blood vessels (glomeruli) and a pipe (tubule), convey urine on its journey south.

Kidneys filter 400 pints of body fluid per day, discarding 1 percent as urine. Waste products are removed while important elements such as sodium and potassium are balanced, and water concentrations kept correct. When dehydrated, our urine is concentrated; if we are drinking a lot, the color is pale. The bladder stores urine for up to eight hours. Additionally, kidneys stimulate red blood cell production, help control blood pressure, and ensure bone health through calcium metabolism. Diseases damaging kidney filtration cause predictable signs, as failure to filter properly allows goop accumulation, impairing human function—sounds like an aircraft fuel system.

Inherited illnesses include polycystic disease where multiple fluid-filled sacks squish good nephrons or faulty genetics cause problems handling consumed substances; subsequent buildups damage the organ. Acute renal (kidney) failure occurs in dehydration, trauma, or heart attacks, becoming chronic if protein leaks into the urine for at least three months. Of acquired causes, raised blood pressure (hypertension) and diabetes are common, preventable, and treatable. Hypertension damages blood-vessel walls and diabetes affects small, internal vessels, while excess sugar floods into urine. Medication abuse (aspirin, acetaminophen, ibuprofen) may cause renal failure, as can various illegal drugs. Glomerulonephritis—inflammation of glomeruli—with renal failure may develop after strep throat or other infection, or in connective tissue diseases such as lupus. Children with poor bladder/ureter valve mechanisms may suffer recurrent urinary tract infections (UTI), which can lead to renal damage. Later in life, repeated or untreated UTI can damage kidneys. High blood concentrations of certain substances, parathyroid organ dysfunction, or problems with the blood itself can manifest as kidney stones, causing severe pain and organ damage.

Symptoms and signs of kidney problems may be absent or might reflect the causative problem such as a sore throat with strep, blood in the urine, or severe pain with stones. Sometimes symptoms are subtle: reduced appetite; insomnia; general fatigue; aching muscles; nausea and vomiting; or dry, itchy skin. Renal failure may present with anemia, puffy face in the morning, reduced or altered urination pattern, “foamy” urine, shortness of breath, or a dry cough because of lung fluid buildup. Lots of stuff to think about, or just one thing—see your doctor if you are worried.

After taking a careful history your physician should check for raised blood pressure; dipstick the urine for blood, protein, and sugar; and order blood and urine tests to evaluate levels of blood urea nitrogen (BUN), creatinine, and glomerular filtration rate (GFR), a measure of how well nephrons perform; it varies with age, sex, body size, and race.

Kidney disease may be prevented by staying fit, thereby lowering blood pressure, cholesterol, and diabetes risk—as little as three days a week, do 30 minutes of exercise—walking, swimming, or cycling. Be careful using over-the-counter pain medications, drink water liberally, and see your doctor for a checkup—more often if you have risk factors. Other than blood pressure and urinalysis, your AME will not do tests to exclude renal disease, so consider extra screening if you have raised blood pressure, BUN, creatinine, or poor GFR. Also, races other than Caucasians are at increased risk.

Therapies are aimed at the causative problem and for raised blood pressure, one specific class of medication—ACE inhibitors—may also improve kidney function. If chronic renal failure develops, filtration can be provided episodically either at home or a hospital using one’s abdominal cavity (peritoneal dialysis) or an external machine (hemodialysis). In many cases, transplanting a new kidney—donated either after death or by a living donor—can change a life. So, if nothing else about this article is relevant to your life, please consider carrying an organ donor card. And give steak and kidney pie a chance. I assure you, kidney juice is not involved in the culinary process.

Email the author at jonathan.sackier@aopa.org.

Jonathan Sackier