The latter can lead to changes in body temperature, mood, and prolactin (see the endocrine and exocrine section for details). Endocrine and exocrine
Prolactin is frequently increased in sarcoidosis, between 3 and 32% of cases have hyperprolactinemia this frequently leads to amenorrhea, galactorrhea, or nonpuerperal mastitis in women. It also frequently causes an increase in 1,25-dihydroxy vitamin D, the active metabolite of vitamin D, which is usually hydroxylated within the kidney, but in sarcoidosis patients, hydroxylation of vitamin D can occur outside the kidneys, namely inside the immune cells found in the granulomas the condition produces. 1,25-dihydroxy vitamin D is the main cause for hypercalcemia in sarcoidosis and is overproduced by sarcoid granulomata. Gamma-interferon produced by activated lymphocytes and macrophages plays a major role in the synthesis of 1 alpha, 25(OH)2D3. Hypercalciuria (excessive secretion of calcium in ones urine) and hypercalcemia (an excessively high amount of calcium in the blood) are seen in <10% of individuals and likely results from the increased 1,25-dihydroxy vitamin D production.Thyroid dysfunction is seen in 4.2–4.6% of cases.Parotid enlargement occurs in about 5–10% of cases. Bilateral involvement is the rule. The gland is usually not tender, but firm and smooth. Dry mouth can occur; other exocrine glands are affected only rarely. The eyes, their glands, or the parotid glands are affected in 20–50% of cases.
In the United Kingdom the prevalence is 16 in 100,000. In the United States, sarcoidosis is more common in people of African descent than Caucasians, with annual incidence reported as 35.5 and 10.9 per 100,000, respectively. Sarcoidosis is less commonly reported in South America, Spain, India, Canada, and the Philippines. There may be a higher susceptibility to sarcoidosis in those with celiac disease. An association between the two disorders has been suggested.There also has been a seasonal clustering observed in sarcoidosis-affected individuals. In Greece about 70% of diagnoses occur between March and May every year, in Spain about 50% of diagnoses occur between April and June, and in Japan it is mostly diagnosed during June and July.The differing incidence across the world may be at least partially attributable to the lack of screening programs in certain regions of the world, and the overshadowing presence of other granulomatous diseases, such as tuberculosis, that may interfere with the diagnosis of sarcoidosis where they are prevalent. There may also be differences in the severity of the disease between people of different ethnicities. Several studies suggest the presentation in people of African origin may be more severe and disseminated than for Caucasians, who are more likely to have asymptomatic disease. Manifestation appears to be slightly different according to race and sex. Erythema nodosum is far more common in men than in women and in Caucasians than in other races.