Z THET1,2, S MALALASEKERA3, N AL-SAFFFI3,T HAN1,2, C HAN1, Y HEIN1, R HASELL1
1Department of Nephrology, Central Queensland Hospital and Health Service, Rockhampton, Australia, 2University of Queensland, Rural Clinical School, Rockhampton, Australia, 3Department of General Medicine, Central Queensland Hospital and Health Service, Rockhampton, Australia
Background: In patients with Hepatitis B Virus, there are approximately 10 cases of Tenofovir related Fanconi Syndrome but no report of nephrogenic diabetes insipidus.
Case report: A 54 year old female with hepatitis B virus on tenofovir for 1 year presented with polyuria and acute urinary retnetion. There was no history of diabetes, thyroid, kidney and intracranial pathology. The patient had acute transverse meyelitis that was treated successfully with steroid and plasmapharesis, however polyuria (10L/day) persisted beyond an accepted time frame. As HBV-PCR was negative, tenofovir was ceased. Her full blood count, inflammatory makers, blood sugar, thyroid, kidney and liver function tests were normal. Urine didn’t show haematuria or protienuria. Renal imaging showed no evidence of obstructive uropathy or chronic kidney disease. MRI brain excluded any intracranial lesions.Primary polydipsia was excluded as urine osmolality was not elevated > 500 mosmol/kg during 8 hour water deprivation and the patient responded to DDAVP significantly. Submaximal response to DDAVP at 30% excluded complete nephrogenic DI and complete central DI. Normal ADH result and resolution of polyuria after cessation of an offending drug suggested both complete and partial central DI was unlikely. A submaximal rise in urine osmolality (358mmol/kg) with DDAVP producing elevation of urine osmolality of approximately 30% suggested a diagnosis of partial nephrogenic DI. Polyuria resolved 6 weeks after tenofvoir therapy alone was discontinued.
Conclusion: Patients receiving tenofovir must be monitored closely even several months after initiation of treatment as the drug can cause nephrogenic DI. Combinging plasma ADH assay with water deprivation testing can lead to greater accuracy in differentiating the different forms of DI.
Dr Zaw Thet is a full time Nephrologist from Central QLD Renal Service. He is also a Director of Physician Education and a member of Central QLD Clinical Senate. He is a leading investigator of local and state research projects.