The most common cause of primary hyperaldosteronism is Conn’s syndrome (80%), and treatment resistant hypertension with hypokalaemia in pregnancy should prompt investigation for this. There is physiological up-regulation of the rennin-angiotensin system during pregnancy, resulting in secondary hyperaldosteronism. The true incidence of Conn’s syndrome in pregnancy is unknown but low, and vague presentations make diagnosis and management a dilemma.
A 25 year old primigravida presented at 26 weeks with hypertension, proteinuiria and bilateral leg oedema. She had an emergency caesarean section for severe pre eclampsia. Persistent hypokalaemia lead to a subsequent diagnosis of Conn’s syndrome. She had normal adrenal imaging. She began pharmacological treatment with spironolactone. Currently she is 24/40 into her second pregnancy.
Spironolactone is contraindicated due to its teratogenic effects particularly virilisation of male fetuses. She has been commenced on low dose Aspirin and oral potassium supplements. Her renal function and Magnesium levels, along with blood pressure and urinalysis are being monitored regularly.
Studies have shown unsatisfactory hypotensive effects with methyldopa, hydralazine, labetolol, diazoxide and nifedipine. There is limited research available for eplenerone which is structurally similar to spironolactone but weaker and so does not have virilising effects, this is however unlicensed. Although the presentation of pathology can be non specific and “normal” in early pregnancy, treatment resistant hypertension requires assessment for primary hyperaldosteronism. Management has considerable difficulties due to the teratogenicity/lack of evidence on first line pharmacological treatments. So far there is supportive evidence that amiloride is safe and effective and could be used in these cases.
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