Citrate supplementation is widely used in the prevention of recurrent nephrolithiasis with hypocitraturia. Potassium citrate is the most commonly used citrate agent for this indication. In patients with chronic diarrheal syndromes, the absorption of potassium citrate can be affected. We describe a patient who presented with recurrent nephrolithiasis and chronic diarrhea and was found to have severe hypocitraturia despite citrate supplementation with potassium citrate tablets, likely due to inadequate gastrointestinal absorption of citrate from the slow-release wax-matrix tablets.