A 54 year old woman is found to be hypertensive following an annual work medical assessment. Her blood pressure is 170/95mmHg. She was not hypertensive when reviewed the previous year. She is otherwise fit and well, and practices yoga regularly. She has never smoked and drinks only occasional alcohol. She takes no prescribed medication, and denies any over the counter medication use.

As part of the assessment she has some further tests, the results of which are as follows:

Na 140mmol/L

K 2.7mmol/L

Urea 4.1mmol/L

Creatinine 63μmol/L (0.7mg/dL)

Calcium (corrected) 2.4mmol/L (9.6mg/dL)

Liver function tests normal

Thyroid function tests normal

An ECG demonstrates prominent U waves.

• What is the differential diagnosis of her hypokalaemia?
• How would you like to further investigate this woman to establish the cause of her hypertension and hypokalaemia?

MSc students have a think about what you would do and put your thoughts up in the discussion board.