Anesthetic considerations in a parturient with renal tubular
Renal tubular acidosis, associated with hypothyroidism, is rare. Published in the International Journal of Obstetric Anesthesia, the authors present the case of a woman with known renal tubular acidosis and treated hypothyroidism who underwent emergency cesarean delivery under uneventful combined spinal-epidural anesthesia.

• Management of a parturient with renal tubular acidosis and hypokalemia is challenging.

• Combined spinal-epidural anesthesia was used for cesarean delivery.

• Norepinephrine was used to prevent and treat hypotension.

• Postoperative analgesia was provided with a continuous epidural infusion.

A 30-year-old woman had previously been diagnosed as having RTA with hypokalemia and hypothyroidism (possibly autoimmune), was admitted on an emergency basis. During a routine obstetric visit at 36 weeks of gestational age, an abnormal fetal heart rate was detected. As fetal hypoxia was suspected, an emergency cesarean delivery was planned.

The patient had been diagnosed with hypothyroidism four years prior; and subsequently with RTA, two years later. She had been hospitalized several times owing to hypokalemia-induced quadriparetic events. At the time of admission, she was on thyroxine 150 µg once a day and sodium bicarbonate 325 mg thrice daily and potassium chloride 50 mEq/day orally.

On physical examination her skin and mucosa were dry; however, her hemodynamic parameters were within the normal range. Muscle power was equal in both upper and lower limbs. Recent blood investigations revealed a normal free T3, free T4 and 25-hydroxyvitamin D and an elevated TSH of 16.2 uIU/mL (normal 0.5–5.5 uIU/mL).

Immunofluorescence microscopy was positive for antinuclear antibody (ANA), while negative for anti-dsDNA antibody. Her complete blood count, coagulation parameters, liver and renal function tests were in the normal range. Her preoperative arterial blood gas (ABG) analysis (on room air) was pH 7.36, pO2 98.8 mmHg, pCO2 22.5 mmHg, HCO3− 12.6 mmol/L and base deficit 10.5 mmol/L.

Her electrolytes were Na+ 139 mmol/L, Cl− 106 mmol/L, K+ 2.9 mmol/L, Ca+ 1.17 mmol/L and the urinary pH 6.0. The electrocardiogram was within normal limits. Recent whole abdomen ultrasonography reported a single live intrauterine fetus and normal maternal renal anatomy (no nephrocalcinosis).

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