Hydrocortisone replacement dosage influences intraocular pressure in patients with primary and secondary hypocortisolism

BACKGROUND It has been suggested that the variation of intraocular pressure (IOP) during the day follows the diurnal variation of serum cortisol. There is also a higher risk of ocular hypertension and glaucoma in patients taking excessive oral steroid treatment. We assessed whether different replacement doses of hydrocortisone (HC) influenced IOP. METHODS Seventeen patients (six Addison's disease, 11 hypopituitarism; seven males) aged 24-58 years mean 42.7 years and 20 control subjects (nine males) aged 20-59 years mean 38.7 years were studied. On the first visit, the 17 patients had been taking HC replacement doses, 20 mg morning and 10 mg afternoon. Serum cortisol and IOP in both eyes (Goldmann applanation tonometer) were measured at 0900, 1100, 1300, 1500, 1700 hours with HC 20 mg taken after the 0900 h assessment. The dose of HC was then reduced to 10 mg morning and 10 mg afternoon for 1 week and the measurements were repeated in 16 patients, with HC 10 mg taken at 0900 h. RESULTS In the patients the peak serum cortisol occurred at 1100 h after the 0900 h HC dose. Cortisol levels were significantly higher at 1100, 1300, 1500 and 1700 h after taking 20 mg compared to 10 mg HC. The mean (SEM) IOP (mmHg) was significantly higher after 20 mg HC compared with 10 mg HC at 1300 h: 14.7(0.6) v 13.1(0.6) (P = 0.004) and at 1500 h: 14.4(0.6) v 13.1(0.5) (P = 0.04). The total mean (SEM) daily IOP score was significantly higher after 20 mg HC compared with 10 mg HC: 14.5(0.3) v 13.5(0.3) (P = 0.0002). The total mean (SEM) daily IOP score after the 20 mg HC dose compared with the control subjects was: 14.5(0.3) v 13.7(0.3) (P = 0.08). CONCLUSION Intraocular pressures during the day are influenced by the morning hydrocortisone replacement dosage with significantly higher intraocular pressure levels in the early afternoon following 20 mg compared with 10 mg. A morning hydrocortisone dose of 10 mg leads to a more physiological intraocular pressure profile during the day. These data support the view that a daily replacement dose of 30 mg hydrocortisone may be excessive.