Abstract: SA-PO1005

Severe Hyponatremia: A Rapid Correction with Potassium Repletion in a Patient with Lithium-Induced Nephrogenic Diabetes Insipidus

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports

Authors

  • Khan, Sobia N., Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
  • Baharani, Reena, Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
  • Rodenbeck, Dorothy, Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
  • Choy, Terence, Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
  • Yaziji, Muataz, Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
  • Wadhwa, Nand K., Stony Brook Medicine/University Hospital, Stony Brook, New York, United States
Background

Severe hyponatremia is rare in patients with lithium-induced nephrogenic diabetes insipidus (NDI). This can result from a decreased osmoles intake and acute compulsive water drinking exceeding the capacity of the kidney to excrete free water. Rapid over correction of hyponatremia can occur with potassium repletion. We report a case with bipolar 1 disorder (BD1) with NDI who developed severe hyponatremia with compulsive water drinking on a weight loss diet.

Methods

A 51-year-old woman with BD1, HTN and hypothyroidism presented to the ER with altered mental status, tonic-clonic seizure, lethargy and slurred speech. In the ER, she received IV lorazepam and was intubated for airway protection. Physical exam: Wt 76.4 kg, Temp 35.6oC, BP 166/92 mmHg, HR 71 bpm. Heart, lungs and abdomen were normal. Six months ago, her serum Na was 140 mmol/L. Lab data: WBC 10.48 K/UL, Hct 30.1%, platelets 232 K/UL, serum Na 105 mmol/L, K 2.1 mmol/L, Cl 65 mmol/L, BUN 7 mg/dL, Cr 0.78 mg/dL, Ca 7.5 mg/dL, Mg 1.3 mg/dL, PO4 3.1 mg/dL, osmolality 239 mOsm/kg, cortisol 33.2 UG/dL and TSH 2.82 UIU/ml. Urine: Na 48 mmol/L, K 6.0 mmol/L, osmolality 130 mOsm/kg.
She received KCl 160 mmol IV and 180 mmol oral, and MgSO4 4 g IV in first 24 hrs. She received a total dose of DDAVP 16 mcg IV in 24 hours to prevent rapid correction of serum Na. She passed 6600 mL of urine in the first 24 hrs. In the first 12 hrs, her serum Na increased to 117 mmol/L without receiving NaCl solution. With IV infusion of D5W, this rapid increase was reversed and maintained on a serum Na rise of 6-8 mmol/L in 24 hrs. She was extubated the next day. No response to DDAVP was a clue to the diagnosis of NDI. Further history revealed lithium use for 10 years 20 years prior. Her serum Na slowly increased to 133 mmol/L by hospital day 4. She was instructed to eat a regular diet and to drink to thirst with close nephrology and psychiatry follow up. Over a 6 month follow up, her serum Na remained in normal range.

Conclusion

Hyponatremia is typically not seen in NDI. Our patient was able to maintain normal serum sodium until she began decreasing her oral food intake due to obsessive thoughts about her weight along with compulsive water drinking. In addition, in this case rapid overcorrection of hyponatremia resulted from potassium repletion.