Calcium pyrophosphate dihydrate (CPPD) deposition disease is in most cases idiopathic, but there are familial forms and others in connection with metabolic disease.1 One of the metabolic associations is with hypomagnesaemia, frequently because of Bartter’s syndrome (BS).2 Another cause of hypomagnesaemia is Gitelman’s syndrome (GS),3 a hypocalciuric variant of BS. Recent studies confirm that these are different processes, with diverse molecular bases that explain the clinical and analytical findings characteristic of each one of them.4 We present the case of a patient with chondrocalcinosis (CC) and pseudogout in whose study hypomagnesaemia secondary to GS is detected. In our search of the Medline database, we have not found reports of a similar association. However, reading of some of the CC and BS cases leads us to think that we are actually dealing with patients whose GS had not been diagnosed.5-7

The patient is a 43 year old woman without pathological antecedents who consulted because of a four year history of bilateral mechanic knee pain with episodes of acute arthritis that remitted days after treatment with non-steroidal anti-inflammatory drugs. During …