Thyroid status may affect the rate at which
theophylline is metabolised: in hypothyroidism it is decreased. As
thyroid function is corrected with e.g. levothyr- oxine,
metabolism increases and so larger doses of
theophylline are needed.
Monitor the outcome of resolving hypothyroidism, checking that the effects of
theophylline are adequate. Monitor
theophylline levels as necessary.