Thyroid gland diseases vary according to the environment. In sub-Saharan Africa, they are also influenced by population isolation and the absence of food self-sufficiency, both factors affecting the onset and persistence of
iodine-deficiency
goiters. More cosmopolitan diseases are now added to these thyroid disorders. Women are mainly affected (94.2%), most often with euthyroid
goiters (54.7%), followed by
Graves disease (13.1%),
hypothyroidism (8.8%),
thyroiditis (6.6%), toxic multinodular
goiters (6.6 %) and unclassified
goiters (10%) [Gabon]. The paucity of laboratories specializing in endocrinology and of nuclear medicine facilities, the delay in diagnosis that results in compressive or recurrent
goiters, and
endemic goiters are all typical in Africa. In children and adolescents, death rates increase with congenital or acquired
thyroiditis as with delayed physical or mental development. In this environment,
thyroiditis can also be pregnancy-related. Very recent surveys show a prevalence of
endemic goiters of 28.6% in the community of Sekota, Ethiopia, 64-70% in Sahel-Sudan (population aged 10-20 years), 20-29% in KwaZulu-Natal (school children), 14.3-30.2% in Namibia (school children), 0.21% (
congenital hypothyroidism or
cretinism) in Plateau State, Nigeria, 55.2% at Zitenga, Burkina Faso (210 persons 0-45 years), and 10% in Hararé and Wedza, Zimbabwe (newborn TSH >10.1 microIU/mL). The prevalence of
goiters is 43.6% in children emigrating from Ethiopia to Israel. Millet from semi-arid zones contains
apigenin at a concentration of 150 mg/kg and
luteolin at 350 mg/kg, both of which can interfere with thyroid function. The harmful effects of cassava (also known as manioc) are better known: milling cassava reduces its goitrogenic potential. In addition to
iodine deficiency,
selenium deficiency, and the effect of the
thiocyanates in cassava, ion concentrations in soil and
drinking water appear to play a role. The proportion of thyroid surgery indicated for
hyperthyroidism has tripled, now accounting for 18.5% of all such operations. This disorder is found today in subjects older than 50 years, mainly from rural areas, and caused most often by
Graves disease (25 of 51 cases).
Graves disease in young women can cause serious problems during pregnancy; in such cases assessment of the minimal effective dose of
antithyroid agents is essential.
Carbimazole leads to remission in 61% of cases of
Graves disease.
Hypothyroidism can be auto-immune and often in patent forms because of insufficient screening in Africa: 24 cases in Dakar (1984) and 37 others noticed by us (1998). Single-nodule
tumors were assessed in 89 patients in Khartoum: they were found to be simple
goiters in 72% of cases,
follicular adenoma in 13.5%,
cancer in 13.5% (with 6 of the 12 cases follicular, 5 papillary, and 1 anaplastic). The sex ratio for
thyroid cancer in Ouagadougou is 0.22, thus mainly women. It affects mainly women in their 30s.
Thyroid cancer at Ibadan was found to be
papillary carcinoma in 45.3% of cases; follicular forms were seen in 44.5% and this series includes 5% of medullary
cancers (7 cases), with a mean age of 34 years. Already 4 other cases from Francophone sub-Saharan Africa have been noticed.
Iodine deficiency is suggested to play a role because follicular
cancer in southern Africa accounts for up to 55% of
thyroid cancers.
Thyroid cancers in Algeria are associated with low socioeconomic status and characterized by a high prevalence of
cancers discovered at an advanced stage and of
anaplastic carcinomas. Oral
potassium iodate is recommended: 30 mg of
iodate a month or 8 mg every two weeks.
Iodized oil has been recommended by some authors, as well as a combination of
iodine and
sugar, and the iodation of
drinking water; these are in addition to the proposed methods of opening up areas by new infrastructure). In conclusion,
thyroid disease is due predominantly to
iodine deficiency and goitrogenic products, but we also note the increasing emergence of
hyperthyroidism, especially
Graves disease, atrophic auto-immune
hypothyroidism, and
thyroid cancer. The insufficiency of infrastructure in transportation, endocrinology, and nuclear medicine are a public health challenge for the third millennium.