Nephrogenic diabetes insipidus secondary to syphilis infection

Nephrogenic diabetes insipidus (NDI) is caused by partial or complete renal resistance to the effects of antidiuretic hormone. Acquired NDI can be caused by electrolyte imbalances (eg, hypercalcemia), renal/extrarenal diseases (eg, chronic pyelonephritis), and drugs (eg, lithium toxicity). Syphilis has never been reported to cause NDI.

The aim of this study was to report the case of a 56-year-old man with NDI secondary to syphilis.

The 56-year-old patient presented with polyuria and polydipsia lasting more than 40 days. His urine specific gravity was 1.002. He had no history of chronic kidney disease or contact with toxicants. He had normal blood glucose levels. A water-deprivation test and vasopressin administration indicated NDI. His rapid plasma reagin titer was 1:128. The serum Treponema pallidum-particle agglutination test was positive. He reported engaging in unprotected, extramarital sex 6 months before polydipsia onset and thereafter developing a skin lesion on the external genitalia and arthralgia, both of which resolved spontaneously. Examination of renal biopsy specimens showed abundant plasmacytic and lymphocytic infiltration of the interstitium and low and flat tubular epithelial cells, indicating renal tubular injury. Silver staining revealed T. pallidum-like organisms. Immunohistochemical analysis with T. pallidum-specific antibody confirmed the presence of treponemes.

The patient received 2.4 million U of benzathine penicillin im once a week for 3 weeks.

His urine output gradually reduced; he recovered 1 month later. His urine specific gravity was 1.026, and his syphilis rapid plasma reagin titer was 1:8.

Syphilis can cause NDI. The manifestations of syphilis and causes of acquired NDI are diverse.