title: Retrospective study of hyponatremia in gastric cancer patients treated with a combination chemotherapy of 5-fluorouracil and cisplatin: a possible warning sign of severe hematological toxicities?
abstract: BACKGROUND
  Some anti-neoplastic agents induce hyponatremia. The relationship between hyponatremia and other toxicities in gastric cancer patients treated with 5-fluorouracil and cisplatin (FP) was investigated retrospectively to clarify its clinical significance.
  
  
  METHODS
  The subjects were 50 advanced gastric cancer patients treated with FP. Patients' performance status, oral intake, nausea/vomiting, diarrhea, fever, urine volume, presence of ascites or pleural effusion, laboratory data and administration of diuretics, corticosteroid and contents and volume of hydration before and during the first 5 days after chemotherapy were reviewed.
  
  
  RESULTS
  The serum sodium level decreased after initiation of chemotherapy in all patients and the lowest level (nadir) was most frequently observed on day 8 (range, days 2-14), which preceded hematological toxicities. In 10 patients (20%) the nadir of serum sodium was lower than 125 mEq/l. We classified these 10 patients as a low-sodium group and the others into a normal-sodium group. Six (60%) and seven (70%) of the 10 patients in the low-sodium group had complications with grade 3 or 4 leukopenia and thrombocytopenia, whereas only one (3%) and two (5%) were seen in the normal-sodium group (p < 0.0001). Stomatitis and diarrhea were also slightly more severe in the former than the latter group. With respect to sensitivity and probability, receiver operating characteristic curves showed the nadir ((> or = ) or <125 mEq/l) of the serum sodium level was the best marker for both leukopenia and thrombocytopenia.
  
  
  CONCLUSIONS
  Hyponatremia after initiation of chemotherapy with FP may be a warning sign of subsequent severe hematological toxicity.
authors.affiliation: Division of Digestive Endoscopy and Gastrointestinal Oncology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan. nboku@east.ncc.go.jp
authors.forename: N
authors.initials: N
authors.lastname: Boku
authors.forename: A
authors.initials: A
authors.lastname: Ohtsu
authors.forename: F
authors.initials: F
authors.lastname: Nagashima
authors.forename: M
authors.initials: M
authors.lastname: Muto
authors.forename: T
authors.initials: T
authors.lastname: Shinkai
authors.forename: S
authors.initials: S
authors.lastname: Yoshida
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects*; D002945:Cisplatin / Q000009:adverse effects; D019008:Drug Resistance, Neoplasm; D005260:Female; D005472:Fluorouracil / Q000009:adverse effects; D006801:Humans; D007010:Hyponatremia / Q000139:chemically induced*; D007970:Leukopenia / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012964:Sodium / Q000097:blood; D013274:Stomach Neoplasms / Q000188:drug therapy*; D013921:Thrombocytopenia / Q000139:chemically induced*
chemical_list: D012964:Sodium; D002945:Cisplatin; D005472:Fluorouracil