By: James Pitt  Jun. 27, 2018
Hyponatremia, i.e. low blood sodium, is a common electrolyte imbalance. According to the Mayo Clinic, risk factors for hyponatremia include age, certain medications, kidney disease and heart failure (due to their effects on water excretion), and intensive physical activities like marathons.
A May 2017 study in American Journal of Emergency Medicine found that hyponatremia prevalence increases in the summer, especially in the elderly. In non-elderly adults, monthly hyponatremia prevalence averaged 3.74±0.5%, increasing to 4.14±0.2% in the summer. In the elderly, monthly hyponatremia prevalence averaged 10.3±0.7%, rising to 12.52±0.7% in the summer.
Southern Arizona is one of the hottest regions in the United States. According to the NOAA, the average annual temperature for the US as a whole was 54.6°F in 2017. The average temperature for climate regions in southern Arizona from 2013-2016 was 73.5°, 71.1°, and 64.3°.
Dexur analysts examined hyponatremia in southern Arizona. Hyponatremia and other electrolyte disorders are grouped under Nutritional and Miscellaneous Metabolic Disorders with Major Complications or Comorbidities (DRG 640), and without major complications (DRG 641).
At Tucson Medical Center (Tucson, AZ), 26% of DRG 640 discharges were for hyponatremia, equal to the national rate. At all other Southern Arizona hospitals, the rate of hyponatremia was higher. Chandler Regional Medical Center (Chandler, AZ) equaled the statewide rate at 32%. The highest rates in the sample were 43% at Mayo Clinic - Arizona (Phoenix, AZ) and Yuma Regional Medical Center (Yuma, AZ).
The trend was similar for nutritional disorders without major complications. 42% of DRG 641 patients had hyponatremia at Banner Desert Medical Center (Sun City West, AZ), well over the national rate of 36%.
The highest rate of hyponatremia in DRG 641 patients in the sample was at St. Joseph's Hospital and Medical Center (Phoenix, AZ), where 53% had hyponatremia.
For DRGs 640 and 641, from 2013-2016, for the following hospitals: