G2, P1, IUGR in previous pregnancy. Presented in 34/40 of pregnancy with profound lethargy, muscle weakness and fatigue. Found to have normotensive hypokalaemia − 2.6 mmol/l and mild metabolic alkalosis. No preceding vomiting, diarrhoea or nutritional cause. Pre-natal blood results were not available but reported low K+ in 2009. Required intravenous potassium replacement and symptoms improved dramatically with restoring normokalaemia. Results at diagnosis: K+ 2.6 mmol/l, Na − 131 mmol/l, pH − 7.5, bicarbonate − 31.2 mmol/l, magnesium 0.8 mmol/l, renin − 156 mU/l, aldosterone − 3930 pmol/l, 24-h urine collection for calcium and magnesium unfortunately not returned despite prompting. Diagnosis of Gitelman syndrome (GS) was made in the absence of alternative cause. Potassium replacement (Sando K 2 tablets tds) continued for the rest of pregnancy with close K+ monitoring (3.5−4.7 mmol/l). Pregnancy progressed well and growth scans were normal. Underwent IOL at 39/40 and delivered heathy baby (babys potassium − 3.7 mmol/l). Patient s potassium in labour fell to 2.7 mmol/l despite period of stability and stable Sando K dose prenatally and required iv replacement and ECG monitoring in labour.
Discussion: Diagnosis of GS in pregnancy is difficult as biochemistry seen in GS such as rise in renin and aldosterone and increased renal filtration rate, also occur as physiological changes in pregnancy especially in third trimester. Pregnancy in GS is mostly uneventful but association with IUGR, miscarriage and oligohydramnios has been reported. Hypokalaemia can worsen in pregnancy and K+ therefore needs to be closely monitored and supplement dosing may need adjustment. Hyperventilation and anxiety in labour can exacerbate severe hypokalaemia. It is important that the obstetrics team and anaesthetist are aware of the diagnosis as potential issues intrapartum can include arrhythmias, laryngospasm and tetany provoked by K+ drop.