Category: Pituitary Disorders/Neuroendocrinology
Objective : To present a rare case of simultaneous central and peripheral diabetes insipidus (DI).
Methods : n/a
A 27-year-old man with a history of a pure intracranial germinoma, in remission for 1 year, presented to an outside hospital with 1 month of lower back pain, left lower extremity weakness, and urinary incontinence. He was found to have spinal drop lesions, as well as an intra-dural/extramedullary mass encompassing the conus of the spinal cord resulting in cauda equina syndrome.
Shortly after admission, the patient developed hypernatremia to 150 milliequivalents per liter (mEq/L) and urine output (UOP) exceeding 1 liter per hour (L/hr). It was determined he had developed central DI given his increased UOP, hypernatremia, and low urine osmolality in the setting of a newly discovered 2.8 centimeter sellar/suprasellar mass found on an MRI brain. The patient was started on desmopressin (DDAVP). Over the course of the next 3 months the patient’s DI was very challenging to control, failing multiple intra-nasal and oral DDAVP treatment regimens. The patient’s UOP and sodium (Na) eventually achieved stability on subcutaneous DDAVP dosed every 12 hrs.
Nearly 3 months into the patient’s admission, he was started on a new chemotherapy regimen, which included Ifosfamide. The evening after the first dose of Ifosfamide, the patient’s UOP increased dramatically, eventually producing 8.7 L of urine in less than 12 hrs. He became floridly altered, and his Na was found to be 178 mEq/L by the next morning, increased from 149 mEq/L measured 24 hrs prior. It was confirmed he had received his regularly scheduled doses of DDAVP. He was consequently started on an aggressive intravenous (IV) normal saline fluid regimen. Despite receiving a total of 2.5 additional micrograms of subcutaneous DDAVP in the next 24 hrs, his UOP remained elevated at 100-160 mL/hr with no improvement of his Na. After switching him to dextrose 5% water IV solution, the Na gradually decreased to 155 mEq/L by the next morning.
Ifosfamide has a less than 1% risk of nephrogenic DI, and a half-life of approximately 7-15 hrs. This correlates with the duration of the patient’s increased UOP. This, along with his acute onset resistance to DDAVP, suggests that he suffered from acute nephrogenic DI superimposed on his chronic central DI. Ifosfamide was discontinued, and the patient never had a repeat incidence of dual DI.
Conclusion : This case highlights the importance of close surveillance of patients with a known history of central DI, given any new medications, even with rare incidences of nephrogenic DI, may result in mixed DI with potentially detrimental consequences.
Michael Cruz– Endocrinology Fellow, LAC + USC, Alhambra, California
Braden Barnett– Clinical Assistant Professor of Medicine, Keck School of Medicine of the University of Southern California; Department of Medicine; Division of Endocrinology, Diabetes, and Metabolism, Los Angeles, California
Jessica Chan– Endocrinology Fellow, LAC+USC Medical Center
LAC + USC
FELLOWSHIP July 2017–July 2019
Endocrinology, Los Angeles County + University of Southern California
RESIDENCY June 2014–June 2017
Internal Medicine, Santa Clara Valley Medical Center
DOCTOR OF MEDICINE June 2014
University of California, San Diego School of Medicine
MASTER OF ADVANCED STUDIES IN CLINICAL RESEARCH June 2013
University of California, San Diego
BACHELOR OF SCIENCE BIOPSYCHOLOGY MAJOR December 2008
University of California, Santa Barbara
BACHELOR OF ARTS SPANISH MINOR December 2008
University of California, Santa Barbara
American Board of Internal Medicine August 2018
Clinical Assistant Professor of Medicine
Keck School of Medicine of the University of Southern California; Department of Medicine; Division of Endocrinology, Diabetes, and Metabolism
Los Angeles, California
Dr. Barnett completed his undergraduate studies at Stanford University, and subsequently completed his medical school, internship/residency (Internal Medicine), and fellowship (Endocrinology, Diabetes, and Metabolism) at the Keck School of Medicine (KSOM) of the University of Southern California (USC). Upon completing his training, he joined the faculty in the division of Endocrinology, Diabetes, and Metabolism at KSOM of USC as both a clinician in private practice and in the trainees' clinics.
LAC+USC Medical Center
Jessica Chan graduated from UCSD in 2010 with a BA in Human Development. She went on to graduate from Creighton University School of Medicine in 2015 and trained at Lenox Hill Hospital in NYC for Internal Medicine residency. She is now a first year Endocrine Fellow at USC. She became ABIM certified in Aug 2018.