Management of Pre-eclampsia Complicated by Hypokalemia

Diagnosis and Initial Assessment

All women with pre-eclampsia should undergo comprehensive maternal monitoring including blood pressure monitoring, proteinuria assessment, clinical evaluation for clonus, and twice weekly blood tests for hemoglobin, platelet count, liver transaminases, creatinine, and electrolytes including potassium 1, 2
There should be no attempt to classify pre-eclampsia as mild versus severe as all cases can rapidly deteriorate 2

Consider the cause of hypokalemia, which may be related to diuretic use, though diuretics are generally not recommended in pre-eclampsia 3, 4
Consider the cause of hypokalemia, which may be related to renal losses due to pre-eclampsia-related kidney dysfunction 4

BP requires urgent treatment in a monitored setting when ≥160/110 mmHg; acceptable agents include oral nifedipine or intravenous labetalol or hydralazine 2, 5
For BP consistently ≥140/90 mmHg, treatment should aim for a target diastolic BP of 85 mmHg (and systolic BP <160 mmHg) 2
Antihypertensive drugs should be reduced or ceased if diastolic BP falls <80 mmHg 5
First-line oral antihypertensives include methyldopa, labetalol, and nifedipine 3, 5
Avoid ACE inhibitors as they are contraindicated during pregnancy 4

Women with pre-eclampsia who have proteinuria and severe hypertension, or hypertension with neurological signs or symptoms, should receive magnesium sulfate for convulsion prophylaxis 2, 6
Typical magnesium sulfate regimen includes a loading dose of 4g IV or 10g IM, followed by 5g IM every 4 hours or an infusion of 1g/h until delivery and for at least 24 hours postpartum 2, 7

Total fluid intake should be limited to 60-80 mL/h in pre-eclampsia 7
Plasma volume expansion is not recommended routinely in women with pre-eclampsia 6
In the setting of hypokalemia, careful fluid balance is essential as both over-hydration and dehydration can worsen outcomes 7
Avoid NSAIDs if possible, especially with renal dysfunction, and use alternative pain relief 7

Fetal monitoring should include assessment of fetal biometry, amniotic fluid, and umbilical artery Doppler with ultrasound at first diagnosis and thereafter at 2-week intervals if initial assessment was normal 1, 6
More frequent amniotic fluid and Doppler assessments are needed if fetal growth restriction is present 6

Women with pre-eclampsia should be delivered if they have reached 37 weeks' gestation 1, 6
Earlier delivery is indicated for repeated episodes of severe hypertension despite treatment with 3 classes of antihypertensive agents 6
Earlier delivery is indicated for progressive thrombocytopenia 6
Earlier delivery is indicated for progressively abnormal renal or liver enzyme tests 6
Earlier delivery is indicated for pulmonary edema 3
Earlier delivery is indicated for abnormal neurological features 6
Earlier delivery is indicated for non-reassuring fetal status 1, 6

Monitor BP at least every 4-6 hours for at least 3 days postpartum 7
Continue magnesium sulfate for 24 hours postpartum 7
Antihypertensives should be continued postpartum and tapered slowly only after days 3-6 unless BP becomes low (<110/70 mmHg) 7
Follow up within 1 week if still requiring antihypertensives at discharge 7

The combination of calcium channel blockers with intravenous magnesium may cause myocardial depression, requiring close cardiac monitoring 4
Women with pre-eclampsia and hypokalemia should be managed at centers with maternal and fetal medicine expertise, especially if onset is <34 weeks' gestation 2, 6