Fly Well: Getting stoned

The kidneys filter noxious blood constituents, and they moderate blood pressure and red blood cell production. Several factors lead to stones in kidney, bladder, or ureters (tubes joining kidneys and bladder): dehydration causing concentrated urine, increased blood-borne minerals, or urine unable to prevent crystals forming.

Obesity and family history contribute risk, but understanding stone constitution helps ensure prevention. In cystinuria, a rare amino acid condition, stones contain cystine. Most stones, however, are calcium based, often together with oxalate, a common food constituent found in nuts, rhubarb, beets, spinach, and chocolate, among others. With a protein-rich diet, history of gout, and reduced water intake, uric acid stones are common. High vitamin D levels, certain medications and chronic illnesses, and bypass surgery for obesity may provoke stone formation. Each kidney or gallbladder stone may be a tombstone to contained bacteria, so recurrent urinary tract infections are both a cause and effect of kidney stones.

Symptoms may be absent if kidney stones are stationary, or the stones may produce dull aches or blood in the urine—a sign that demands immediate medical attention. However, pain can be sharp, gripping, and extreme, usually felt in the side and back; if the problematic pebble passes into the ureter, pain will move toward one’s groin. Nausea and vomiting are common and urine will turn pink or red. Once in the bladder, pain may abate, only to return with a vengeance when the gritty gremlin endeavors to exit the body, causing constant desire to urinate but only small volumes will pass. If infection is present, urine may appear cloudy and smell awful, and fever with shaking may occur, which merits urgent medical attention. If a stone passes, retrieve it so your doctor can perform analysis to better prevent recurrence—believe me, you will be glad to fish around the toilet if it ensures you never experience that again! You may also have to pee through a mesh strainer to capture fragments for the lab to review.

If stones are suspected, blood tests may reveal excessive minerals or other causative disease processes. Similarly, collecting all urine passed in 24 hours allows analysis of stone-forming substances. Simple x-rays may show stones, but an ultrasound or CT scan will provide a better roadmap.

Acute attack treatment consists of pain and nausea relief; combating any infection; and possibly medication to relax the ureters, facilitating natural stone passage. If stones do not pass spontaneously, they may be retrieved via a telescope introduced through the external urinary tract opening. Larger stones can be fragmented with external shock wave lithotripsy (ESWL)—sound waves that shatter the stone into small, easily passed pieces. A surgical procedure may be required for larger stones. If parathyroid disease is a culprit, the glands may need to be removed.

As always, prevention beats cure, so drink lots of water, reduce oxalate intake if your stone contained this substance, exercise caution taking calcium supplements, reduce animal protein consumption, and limit salt intake. Your doctor may prescribe medications to prevent recurrence such as diuretics or allopurinol, if uric acid is an issue for you. Seek medical advice for your particular situation and consider consulting a dietitian.

From an aeromedical perspective, self-ground with the acute illness—you would be in no condition to fly anyway. If medications are required, check acceptability by FAA; allopurinol is fine, some antispasmodics are not, and those for metabolic treatment are considered on a case-by-case basis.

If this was your first episode, your AME can issue your medical certificate if you provide the treating urologist’s report stating how the stone was discovered; date of ESWL or other treatment; tests to determine likelihood of further stone production; and proof that the stone is gone, or if stones remain, their location and size. If you have just one episode or have a retained stone that is proven to be of stable size, has not blocked the ureter, is deemed unlikely to move by a specialist, and you have no underlying condition likely to lead to further stones, or evidence of kidney disease, the AME can issue in the office.

A kidney stone walks into a bar and the bartender asks, “What will you have?” The stone responds, “Nothing, thanks, I’m just passing through.” May your beach walks have clean sea air and your kidneys be stone free.

Email [email protected]