Question

Kidney stones occur when solid material blocks the flow of urine in the renal system. Although there are many causes, Ca2+ is a common component of the stone itself. If left untreated, Kidney stones can lead to renal failure. You are a Nephrologist treating a patient who has already had one kidney removed. They report that they have experienced nausea, vomiting, and swelling of the extremities (edema.) An MRI shows a kidney stone which has completely blocked the ureter of the remaining kidney. Propose a mechanism whereby the kidney stone would explain the patient’s symptoms.

Answer 1

The kidney stone is caused by deposition of calcium either in kidneys or ureter. This causes obstruction to flow of urine. The pain due to kidney stones is due to stretching, dilation and spasm caused by the obstruction to the ureter.

The renal capsule and the intestine have shared splanchnic innervation. The celiac axis and vagal nerve afferents link the renal pelvis, intestine and the pelvis. The pain in the kidneys will also affect these innervation and cause nausea. The nauseas and vomiting are due to effects on motility in the gastrointestinal tract. Kidney stones cause interstitial edema, which will stretch the kidney capsule.

Increase capillary permeability will case the development of interstitial edema (fluid buildup). The urine buildup due to obstruction will cause hydronephrosis. This hydronephrosis or edema is because of decreased ability of the kidneys to filter waste. Kidneys normally allow protein such as albumin from blood from entering the kidneys. In case of kidneys stones, the kidneys will eventually lose their filtration ability. This also leads to increased loss of protein in urine. As a result, the blood capillaries cannot efficiently remove interstitial fluids. This leads to accumulation of interstitial fluid, which results in edema.