A 12-year-old boy, with intermittent abdominal pain from 3 years of age, presented with increased frequency of right lower quadrant pain (at least three episodes per week over the past six months) and pain during micturition affecting school attendance. His family history included referred urolithiasis. An abdominal ultrasound performed 1 year before our visit showed a small stone of 4 mm in the right renal pelvis for which he did not receive any therapy. The patient brought 25 hard stones with irregular outline, 2–8 mm in diameter, of deep brown/grey colour that he claimed to have found in his underwear (figure 1). On examination, he looked well with normal vital signs and unremarkable cardiorespiratory and abdominal examinations. Plasma creatinine was 0.41 mg/dL (36.1 μmol/L), urinalysis and urine tests were all normal (including 24 hour calcium, phosphorus, oxalate, citrate, uric acid and cystine). Repeat kidney and urinary tract ultrasound showed no evidence of calculi.

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Figure 1

Twenty-five hard formations brought along by the patient from home.

Question 1 Which is the most likely diagnosis?

1. Cystinuria.

2. Dent disease.

3. Idiopathic urolithiasis.

4. Factitious disorder imposed on self.

5. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis.

Question 2 How would you confirm your diagnostic suspicion?

1. Reassurance and clinical follow-up.

2. Mass spectrometry of stones.

3. CT urography.

4. Increase oral fluid intake and administration of potassium citrate.

Question 2

Question 3 How would you manage this condition?

1. Administration of placebo.

2. Psychological consultation.

3. Observed 24 hour urine collection.

4. All of the above.

Answers can be found on page 2.