Myopathy, hypokalaemia and pica (geophagia) in pregnancy

Editor,

Pica describes the persistant ingestion of nonnutritive substances.¹ Geophagia describes pica of clay.² We present a case of geophagia resulting in hypokalaemic myopathy.

Case History

A 29 year Gravida 3 Para 2 presented to a tertiary referral centre in Cape Town, South Africa, at 30⁺⁴ weeks gestation. She gave a two week history of photophobia, vomiting and weakness of the left side of her body. no other symptoms were reported. fetal movement was reported to be normal. Her two previous pregnancies, in 1997 and 2001, were uneventful and resulted in normal vaginal deliveries at term. She had no significant medical or family history, was not on medication and did not report any allergies. She was a non-smoker and non-drinker. She was from the coloured community in Cape Town. She was a single mother, lived in an informal dwelling settlement, and had no monthly income.

She booked at 22 weeks gestation and an anomaly scan reported no fetal abnormality. Her booking Body Mass Index was 33, BP 110/85 mmHg, Hb 9.3g/dl, blood group A+ve, no abnormal antibodies, VDRL negative and HIV negative. Her pregnancy was uneventful up until presentation at hospital.

Examination of the cardio-vascular, respiratory and gastrointestinal systems was normal. Neurological assessment of the central nervous system was normal. Proximal muscle strength was reduced bilaterally with muscle groups demonstrating 4/5 strength. Biceps and patellar reflexes were reduced and plantar reflexes were normal. Sensation was normal. The provisional diagnosis was a myopathic process of unknown aetiology.

Haematological investigations showed a Hb of 9.9g/dl, WCC 11.2×109/L, Platelets 391×109/L and an ESR of 73mm in 1 hour. Biochemistry showed a sodium of 145mmol/L, potassium 1.5mmol/L, urea 2.2mmol/l, and creatinine 116μmol/L. Liver function tests were also abnormal. Her creatine kinase was 9920U/L. Further investigations as an in-patient included and EMG, MRI scan of brain and muscle biopsy. The EMG reported features in keeping with a myopathy. The MRI scan and muscle biopsy were normal. Biophysical assessment of the fetus was reassuring.

Further questioning of the mother revealed that throughout the pregnancy she had regularly been eating clay from outside her house. It was impossible to accurately quantify the amount eaten. The patient's symptoms slowly responded to intravenous and oral potassium supplementation over 14 days. Her liver function and renal function returned to normal. She was discharged 18 days after admission to hospital. Her care, for the remainder of her pregnancy, was in the community. Further follow-up information is not available. The patient did not have a telephone land line nor a cellphone. A request was made to the community services to follow-up the patient. On receiving the address, we were told that they only went into the patient's district with a police escort and our request was not justified.

DISCUSSION

The aetiology of pica is not known. Theories on pica range from nutritional deficiencies and psychological problems to obsessive-compulsive behaviour and specific brain lesions.^3,4 Pica can cause a number of serious conditions including iron-deficiency anaemia, bowel obstructions and perforations, lead poisoning, and helminthnic infestations.⁵ This is only the second report in the literature of geophagia causing hypokalaemic myopathy in pregnancy.⁶ The pathophysiology, it is suggested, is that clay binds to potassium in the gut. This leads to increased intestinal excretion of potassium, resulting in hypokalaemia.⁷ It appears that the effect is dose dependent on the amount of clay ingested.

Unfortunately, our patient was lost to follow-up. This also occured in the other reported case.⁶ The long-term maternal, fetal and neonatal outcomes in the severely hypokalaemic mother, would be of interest.

The author has no conflict of interest.