Poster Presentation - SOMANZ ASM Society of Obstetric Medicine of Australia and New Zealand ASM 2023

Hypokalaemia in pregnancy – prevalence, underlying causes, and an approach to investigation (#48)

Jinwen He 1 , Adam Morton 1
  1. Endocrinology, Mater Hospital, Brisbane, Queensland, Australia

Introduction: There have been limited studies regarding the prevalence and aetiology of hypokalaemia in pregnancy. While subject to reporting biases, commonly reported causes in literature include hyperemesis gravidarum, Gitelman syndrome, primary aldosteronism and renal tubular acidosis. 1, 2, 3,4,5,6,7,8,9,10  A United States nationwide population study has found hypokalaemia in pregnancy is associated with younger age, African American origin, lower income level, higher comorbidity index as well as complications including gestational hypertension, hyperemesis gravidarum and postpartum haemorrhage.11

 

Methods: The objective of this study was to investigate the prevalence and aetiology of hypokalaemia in pregnancy. This was a five-year retrospective audit of women who developed hypokalaemia during pregnancy and within 3 weeks postpartum at Mater Hospital, Brisbane from 2017 to 2021.  Serum potassium, cause(s) of hospitalization and investigations for hypokalaemia were obtained from hospital records.

 

Results:

One hundred and ten women developed hypokalaemia, representing 0.36% of total births. Hypokalaemia occurred in the 1st trimester in 10% of patients, 2nd trimester in 20%, 3rd trimester in 41% and in the immediate postpartum period in 29%. Ninety-one per cent of patients had mild to moderate hypokalaemia (K 2.6-3.1mmol/L), while 9% had severe hypokalaemia (K<2.6mmol/L).

The most common associations of hypokalaemia were infection (38%), vomiting (18%), hypertensive disorders (12%) and postpartum haemorrhage (9%). There was a disproportionate of women of African descent, as 20% of patients with hypokalaemia were African, while African women only represented 7% of total births. This could be potentially related to the practice of geophagia.

Only 17 out of 110 patients had further investigations to determine the aetiology of hypokalaemia. For the 24 patients with no underlying cause, only 5 (21%) had further investigations.  Only 12 patients had assessment of urinary potassium, and this was delayed by a mean of 6 days after the diagnosis of hypokalaemia.

In the 15 patients who had aldosterone and renin levels assessed, 9 had hyporeninemic hypoaldosteronism, which is atypical in pregnancy, as this is usually associated with elevation of both renin and aldosterone levels. We hypothesize that there could be multiple factors contributing to this, including pre-eclampsia, intravenous fluid administration as well as the practice of geophagia.

 

Conclusions:

A major finding was the inadequate investigation of hypokalaemia, especially measurement of urine potassium pre-replacement. This was particularly concerning where an obvious cause was not apparent at presentation. A proposed flowchart for investigation of hypokalaemia in pregnancy is included.

 

 

  1. Walch A, Duke M, Auty T, et al. Profound Hypokalaemia Resulting in Maternal Cardiac Arrest: A Catastrophic Complication of Hyperemesis Gravidarum? Case Rep Obstet Gynecol 2018; 2018: 4687587.
  2. Lassey SC and Robinson JN. Rhabdomyolysis After Hyperemesis Gravidarum. Obstet Gynecol 2016; 128: 195-196.
  3. Fukada Y, Ohta S, Mizuno K, et al. Rhabdomyolysis secondary to hyperemesis gravidarum. Acta Obstet Gynecol Scand 1999; 78: 71.
  4. Moustakakis MN and Bockorny M. Gitelman syndrome and pregnancy. Clin Kidney J 2012; 5: 552-555.
  5. Raffi F, Fairlie FM, Madhuvrata P, et al. Pregnancy with Gitelman's syndrome. Obstet Med 2011; 4: 39-41.
  6. de Arriba G, Sanchez-Heras M and Basterrechea MA. Gitelman syndrome during pregnancy: a therapeutic challenge. Arch Gynecol Obstet 2009; 280: 807-809.
  7. Landau E and Amar L. Primary aldosteronism and pregnancy. Ann Endocrinol (Paris) 2016; 77: 148-160.
  8. Vidyasagar S, Kumar S and Morton A. Screening for primary aldosteronism in pregnancy. Pregnancy Hypertens 2021; 25: 171-174.
  9. Seeger H, Salfeld P, Eisel R, et al. Complicated pregnancies in inherited distal renal tubular acidosis: importance of acid-base balance. J Nephrol 2017; 30: 455-460.
  10. Srisuttayasathien M. Hypokalemia-Induced Rhabdomyolysis as a result of Distal Renal Tubular Acidosis in a Pregnant Woman: A Case Report and Literature Review. Case Rep Obstet Gynecol 2015; 2015: 947617.
  11. Yang CW, Li S and Dong Y. The Prevalence and Risk Factors of Hypokalemia in Pregnancy-Related Hospitalizations: A Nationwide Population Study. Int J Nephrol 2021; 2021: 9922245.