Hypopituitarism is considered to be a rare disorder. There are less than 200,000 patients with hypopituitarism in the United States.
On a global basis, the incidence is estimated to be 4.2 cases per 100,000 per year, and the prevalence is approximately 45.5 cases per 100 000 people. These figures are indicative of the general population and have not been adjusted for gender or specific groups at risk.
It is generally accepted that some population groups are at an increased risk of permanent pituitary deficiency and hypopituitarism. This includes individuals that have a history of traumatic brain injury or aneurysmal subarachnoid hemorrhage. However, the incidence of the condition in these populations remains to be determined, as there is insufficient research to estimate epidemiological parameters.
Other risk factors, such as age, gender, ethnic origin and geographical location, have not yet been identified and there are no clear trends in the incidence or prevalence of hypopituitarism.
Patients with hypopituitarism show higher rates of mortality associated with cardiovascular and cerebrovascular causes when compared to the general population. This is usually thought to be linked to a deficiency in growth hormone (GH), although other pituitary hormones may also be involved.
The first scientific study to investigate the prevalence and incidence of hypopituitarism was carried out by Regal et al in Spain with a sample population size of 146 000. In this group of people, the prevalence of hypopituitarism was found to be 45.5 cases per 100,000.
The study population comprised adults residing in South Galicia (north-western Spain). The diagnosis of hypopituitarism was made on baseline and hormonal dynamic tests. The first survey found the prevalence of hypopituitarism to be 29 per 100 000. The second survey found it to be closer to 45.5 per 100 000.
Of these patients, the most common cause of the condition was a pituitary tumor (61%). Approximately half of all patients had a deficiency in multiple (3-5) hormones, with a deficiency in luteinizing hormone (LH) and follicle-stimulating hormone (FSH) being the most common.
Another study by Fernandez-Rodriguez et al investigated the mortality and survival rate in patients with hypopituitarism. This study involved 209 adult patients with the condition, selected from a population of over 400 000, who were followed for a period of ten years.
The standardized mortality rate was 8.05, which is eight times higher than in the general population. It was highest in young males. However, reduced survival rates were recognized to be also related to other coexisting or concurrent factors such as cancer, a history of radiotherapy, a high BMI, acromegaly and diabetes mellitus not under control. Further research is required to support these findings.
The clinical symptoms of hypopituitarism are usually non-specific. This makes it a difficult condition to identify and its epidemiological studies are even more challenging. However, it is important that research is done to improve the understanding of this condition, as it has the potential to cause permanent disability and increase the mortality rates.
Some medical scientists have expressed that the true prevalence of the disorder is likely to be considerably greater than indicated in these studies, due to the known difficulties in diagnosing the condition. Based on this, they recommended that hypopituitarism should not be viewed as a rare disease. They also put forth the opinion that recommendations for treatment by a general practitioner should be initiated.