The incidence for all pituitary adenomas is estimated at 80 million persons per year. An increase in the incidence is reported in the time period 1958-1991 in Sweden3. The peak incidence occurs in the fourth to the sixth decade of life5. Incidence and prevalence numbers for the Netherlands are not available.
In a systematic review, the prevalence of pituitary adenomas in the general population has been estimated at 16.7% (14.4% in autopsy studies and 22.5% in radiologic studies). The prevalence of macroadenomas (>1 cm) has been estimated at 0.16-0.2%6. These figures contradict the conventional view of pituitary tumours as rare; pituitary adenomas are in fact common in the general population.
Approximately 25% of all pituitary adenomas are clinically non-functioning/ non-secreting (NFA). The incidence is estimated at 10 per million persons per year. In Belgium, the prevalence of clinically significant non-secreting pituitary adenomas was 138/1.000.000. The male to female ratio is estimated at: 3 : 28.
The incidence of prolactin producing pituitary adenomas (PR) is estimated at 6-10 per million persons per year and the prevalence at 60-100 per million9. A female preponderance is observed of 20 to 1 in microadenomas; in macroadenomas female to male ratio is equal.
The incidence of growth-hormone producing pituitary adenomas (GH) is estimated at 4-6 per million persons per year and the prevalence at 40-60 per million9,10. The incidence of ACTH producing pituitary adenomas (ACTH) is estimated at 2-3 per million persons per year and the prevalence at 20-30 per million9.
TSH (Thyrotrophinoma) and LH/FSH (Gonadotrophinoma) are rare pituitary ade-nomas9. Because of their rarity these tumours are not discussed in detail.