Fred, a fit and healthy 44-year-old, was working outside one warm summer afternoon. When he returned home by the end of the day, his lower back felt sore and he felt nauseated. His wife made him dinner, but he was not hungry and chose to go to bed instead. Fred’s symptoms progressed, and soon he was rolling on the bed with excruciating pain. He said his back hurt as well as his stomach and groin area. The pain would ease off only to return a short while later, and when it did, Fred would begin to sweat and run to the bathroom to vomit. His wife became concerned and started the car. When his symptoms abated, she helped him into the car and rushed him to the hospital.1. At the hospital, an abdominal radiograph showed the presence of renal calculi in Fred’s right ureter (urolithiasis). What is the mechanism of stone formation in the kidney? What is the role of citrate in the kidneys?2. Why would the administration of calcium supplements be useful for a patient with calcium oxalate stones?3. Hydronephrosis can be a complication of renal calculi. What is hydronephrosis? How does back pressure occur in a kidney, and what physiologic mechanism is responsible for nephron damage when back pressure is present?
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Introduction:
This case study presents us with Fred, a 44-year-old man who presented to the hospital with severe back pain and other uncomfortable symptoms. Upon the radiological examination, it was discovered that he had developed renal calculi in his right ureter. This discussion aims to answer some relevant questions about urolithiasis and its complications.
1. The mechanism of stone formation in the kidneys and the role of citrate:
The formation of stones in the kidneys results from the aggregation of insoluble crystals in the urine. The most common substances that form kidney stones are calcium, oxalate, and urate. The presence of an underlying disease or medical condition such as hyperparathyroidism, obesity, or inflammatory bowel disease can increase the risk of stone formation. As for citrate, it is a natural inhibitor of stone formation. It inhibits the growth and aggregation of crystals by binding to calcium ions in the urine, leading to their excretion. Furthermore, citrate increases urine volume and alkalinity, which also negatively affects crystal formation.
2. The usefulness of calcium supplements in calcium oxalate stones:
Calcium is a crucial component of kidney stones, particularly calcium oxalate stones. However, adding calcium supplements to the diet of a patient with calcium oxalate stones may reduce the risk of stone formation. This is because calcium from supplements binds to the oxalate in the intestine and prevents its absorption in the body. As a result, less oxalate is available for kidney stone formation.
3. Hydronephrosis, back pressure in the kidney, and the physiologic mechanism responsible for nephron damage:
Hydronephrosis is a condition where there is fluid buildup in the kidney as a result of obstruction in the flow of urine. Back pressure occurs in the kidney when urine is unable to flow freely due to an obstruction or blockage of the ureter, leading to the accumulation of fluid and increased pressure. The damage to the nephron occurs due to the ischemic injury that results from the decreased blood flow and oxygen supply in the affected part of the kidney. The pressure from the obstruction eventually affects the glomerular filtration rate and renal blood flow, leading to damage to the nephron and possible loss of kidney function.
