The symptoms: The man visited a medical center after experiencing five days of pain on the right side of the lower back, as well as a burning sensation during urination and a fever higher than 102.2 degrees Fahrenheit (39 degrees Celsius).
What happened next: During a physical examination, doctors noted that the right side of the man’s abdomen was painful to the touch. His urine was cloudy, but his heart rate, blood pressure, and respirations were within the normal range.
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The diagnosis: Blood tests showed that the man had elevated levels of leukocytes, white blood cells that fight infection. A urine culture identified a type of bacteria called Klebsiella pneumoniaewhich is often associated with urinary tract infections, the doctors wrote in a report on the case. Together, these findings confirmed that the man had an active infection.
But in addition, an ultrasound and a CT scan of the patient’s abdomen revealed something unexpected: a third kidney, also known as a supernumerary kidney. It was fused with the man’s right kidney, creating a horseshoe shape.
A supernumerary kidney is a congenital anomaly that is thought to appear during fetal development. It appears due to abnormal cell division in the cord that later forms the kidneys. A redundant kidney can sometimes lead to kidney infectionsbut the condition does not always affect normal kidney function and often goes undetected, according to the report.
In this case, the patient’s left and right kidneys were swollen and showed accumulations of limestone or mineral crystals. These hard crystals form when the urine is more concentrated; small “stones” often pass normally when urinating, but can lead to infection if they remain untreated in the kidneys.
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The signs of infection were more severe in the left kidney, with a build-up of limestone in the left ureter, the tube that connects the left kidney to the bladder.
The treatment: Doctors inserted a thin plastic tube, called a stent, into the left ureter to help with urine drainage. They then gave the man intravenous courses of the antibiotics piperacillin and tazobactam three times a day, as well as the antibiotic levofloxacin every other day.
After 48 hours of medication and hydration, the patient’s condition improved. He was discharged and told to follow up in a month to have the stent removed and to manage the build up of the kidney stone.
What makes the case unique: Supernumerary kidneys are extremely rare, with fewer than 100 new cases reported worldwide each year.
A fused “horseshoe” appearance with another kidney is even rarer, with only five cases reported in the scientific literature. Third kidneys may also be completely separate or loosely connected to another kidney by a thin layer of tissue.
Sometimes a patient learns about their extra kidney during treatment for an unrelated condition. For example, a man from Brazil discovered he had a third kidney after he visited a hospital for lower back pain caused by a herniated disc, Live Science previously reported. When doctors performed a CT scan of the painful area, they found a redundant kidney fused to the right kidney near the man’s pelvis. All three kidneys appeared to be functioning normally and were not the cause of his discomfort in that case.
This article is for informational purposes only and is not intended to provide medical advice.
Nimkar, S. V., Yelne, P., Gaidhane, S., Acharya, S., Kumar, S., & Batra, N. (2022). Supernumerary kidney (triple kidney) with horseshoe malformation: A case report. Cureus.https://doi.org/10.7759/cureus.31436
