TW is a mildly obese 52-year-old man. He presents to the emergency room complaining of nausea and severe, intermittent lower back pain that is radiating to the groin. These symptoms have progressively worsened over a period of 24 hours. He also reports that his urine volume has been less than normal for the past 3 days.
After taking a complete history and performing a physical examination, the physician learns that TW?s medical history is significant for hypertension, hypercholesterolemia, and type 2 diabetes. He also had an episode of gouty arthritis about 2 months ago, for which he was treated with indomethacin 50 mg every 8 hours as needed and colchicine 0.6 mg every 6 hours for approximately 4 days. His medications on admission are as follows:
The physician suspects that TW has a kidney stone and tries to determine the cause.
With further evaluation, the physician determines that TW is suffering from a uric acid kidney stone. After dealing with the current stone, the physician wants to treat TW with medication for the prevention of future kidney stones. He asks the pharmacist working in the emergency room what she would recommend.
The pharmacist recommends allopurinol 100 to 300 mg daily, given orally as a single or divided dose. She explains that, by lowering both serum and urine concentrations of uric acid below its solubility limits, allopurinol prevents or decreases urate deposition, thereby preventing the occurrence or progression of both gouty arthritis and urate nephropathy. Potassium citrate also can be given to increase citrate levels, which are the main natural inhibitor of kidney stones. The usual dose is 10 to 20 mEq 2 or 3 times daily with meals.
The physician is impressed with the pharmacist?s knowledge about kidney stones and takes her recommendations. He asks the pharmacist to discuss the medication with TW and to advise him on nonpharmacologic ways to avoid another kidney stone in the future.