Brief Answer: can occur due to the low calorie diet Detailed Answer: HI, thanks for using healthcare magic The HCG diet normally consist of using this hormone in combination with a very low calorie diet.It is not the HCG itself that is causing the stone but the rapid weight loss due to the very low calorie diet Kidneys stones are a possible combination of this diet and any dietary program that is associated with rapid weight loss. This is thought to occur due to rapid breakdown of lean muscle mass and poor hydration that may also occur. The rapid breakdown of the body tissues result in the formation of various substances that must be filtered by the kidneys . These substance alter the composition of the urine and increase the risk of stone formation. In most cases the urine becomes more acidic. To reduce the acidity of the urine your doctor may advise: (1)taking a supplemental or a prescription of citrate such as potassium citrate (2)drinking alkaline mineral water. In general it is important to drink a lot of fluids, this would help flush your present stone and reduce the chance of future formation. The treatment of your current stone would depend on its size. A small stone is treated with pain medication and the use of copious amount of fluids( to help it pass). Larger stones may need other treatment such as shock wave lithotripsy where a machine is used to reduce the size of the stone. There are also other surgical options. I hope this helps, feel free to ask any other questions

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