title: A young boy with recurrent headache, lethargy, and hyponatremia.
abstract: BACKGROUND
  To investigate and differentiate the causes of hyponatremia in an 8-y old boy.
  
  
  METHODS
  An 8-y boy presented with headache, vomiting, and diplopia. Magnetic resonance imaging of the brain confirmed a mass in the pineal region. Pathology report demonstrated a mixed germ cell tumor with a yolk sac component. A multi-agent chemotherapy and radiation regimen was initiated. He developed hyponatremia, with sodium concentrations varying from 116 to 133 mEq/l.
  
  
  RESULTS
  Serum levels of sodium, chloride, phosphorous, uric acid, and osmolality were low. Serum α-fetoprotein, β-HCG, and lactate dehydrogenase were highly elevated. Urine sodium and osmolality were increased.
  
  
  CONCLUSIONS
  These presentations suggest that the patient has cerebral salt-wasting syndrome caused by intracranial germ cell tumor. Recognition and differentiation of cerebral salt-wasting syndrome from other disorders are essential.
authors.affiliation: Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States.
authors.forename: Liyun
authors.initials: L
authors.lastname: Cao
authors.affiliation: Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Wagar
authors.affiliation: Department of Laboratory Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, United States. Electronic address: qhmeng@mdanderson.org.
authors.forename: Qing H
authors.initials: QH
authors.lastname: Meng
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002648:Child; D003937:Diagnosis, Differential; D006261:Headache / Q000097:blood / Q000150:complications* / Q000628:therapy; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000150:complications* / Q000628:therapy; D007177:Inappropriate ADH Syndrome / Q000097:blood / Q000209:etiology* / Q000628:therapy; D053609:Lethargy / Q000097:blood / Q000150:complications* / Q000628:therapy; D008279:Magnetic Resonance Imaging; D008297:Male; D009373:Neoplasms, Germ Cell and Embryonal / Q000097:blood / Q000150:complications* / Q000628:therapy
keywords: Headache; Hyponatremia; Intracranial germ cell tumor; Osmolality