Kidney Stones, Pilots, and Medical Certification

By ALPA Staff

When considering the kinds of health conditions that could prevent you from flying your next trip, kidney stones probably aren’t among your top concerns. However, the National Kidney Foundation points out, “Over half a million people go to emergency rooms for kidney-stone problems every year.” The organization notes that the lifetime risk for men is approximately 19 percent and 9 percent for women.

Kidney stones are common enough that FAA aviation medical examiners (AMEs) have dedicated CACI (conditions AMEs can issue) worksheets, with detailed instructions that outline condition-specific requirements, for pilots suffering from this debilitating and sometimes extremely painful condition.

Kidneys occasionally produce hard deposits made of minerals and salts in the urine, commonly known as stones. These masses can range in size from very small to exceeding 22 millimeters. Depending upon their volume and shape, they can cause serious pain when transitioning through the kidney and ureters to the bladder.

In some cases, stones can get stuck and, depending upon location, can block urine flow. These obstructions can result in infections or other complications that require surgery.

According to the Aviation Medicine Advisory Service, ALPA’s Aeromedical Office, “Symptoms of a kidney stone include severe pain in the flank, which is felt just below the rib cage and above the waist, usually on only one side of the back. The pain may spread to the lower abdomen, groin, and genital area. Other symptoms include blood in the urine, painful or frequent urination, and nausea and vomiting.”

The most common risk factors are dehydration, obesity, and diets high in protein, salt, or sugar. Genetics can also play a role, as can certain medical conditions, including high blood pressure. Physicians will diagnose kidney stones based on medical history, a physical exam, blood and urine lab work, and imaging tests. The most common elements found in kidney-stone deposits are calcium, uric acid, and struvite. Determining a stone’s composition is important because the compounds will help determine the cause as well as a plan for prevention.

One of the best things to do to avoid kidney stones is to drink plenty of water. Doing so will increase the frequency of urination, which will dilute the concentration of urine minerals and salts and reduce the chances of stone formation.

Treatment for kidney stones can include increased urine output and medication for managing pain. Large quantities of fluids are recommended to flush the stone through the urinary system. In the case of larger stones, several medical procedures are available, including lithotripsy, a noninvasive procedure directing ultrasonic or shock waves at the deposits to break them into smaller pieces so that they can more easily pass through the body.

Another option is nephrolithotomy, which involves a surgeon inserting a small tube in the patient’s back to locate and remove the stones. Alternatively, ureteroscopy involves the use of a small telescope through the urethra, bladder, and ureter to detect and withdraw the stones.

The FAA will certify pilots who’ve had a single episode of kidney stones to fly after all stones are cleared and they’re stable and healthy. Pilots with retained stones may be cleared with a special issuance if they’re not experiencing pain or signs of impending passage. Those who have a history of recurrent stones may receive a special-issuance medical certificate if they meet the necessary requirements. They will then be required to submit reports for several years when taking FAA medical exams.

Dr. James Daniel, an FAA AME, a Transport Canada civil aviation medical examiner, and an ALPA Canada aeromedical consultant, encourages affected pilots to work closely with their physicians. He notes that, in principle, Transport Canada’s policy regarding kidney stones is similar to that of the FAA. However, most files involving kidney stones require review by Transport Canada Civil Aviation Medicine.

Have Questions?

U.S.-based ALPA pilots with questions can contact the Aviation Medicine Advisory Service, ALPA’s Aeromedical Office, Monday–Friday 8:30 a.m. to 4:00 p.m., mountain time. Additional information is available on the AMAS website, including related materials in its medical article database. ALPA members based in Canada can call ALPA Canada’s aeromedical consultant at 403-389-3032 for assistance.

This article was originally published in the April 2024 issue of Air Line Pilot.

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