A brief history of hypothyroidism
The word “myxoedema” was first used by Ord in 1878 to describe the mucin deposits in subcutaneous tissue.³ This was officially recognised by a committee appointed in 1883 by the Clinical Society of London as being caused by changes in or destruction of the thyroid gland. Semon had previously suspected that thyroid deficiency caused myxoedema. 4 Thus severe changes in the thyroid and the resulting symptoms were identified, and by 1892 oral thyroid preparations, 5 using animal thyroid were being prescribed or injected. 6 However the concept of mild or minor hypothyroidism was not fully discussed or defined until 1915.
In 1917 McCarrison wrote: “the minor manifestations of thyroid defect are of very common occurrence”. He termed these “manifestations” as “minor thyroid insufficiency”. Significantly he referred to hypothyroidism as either the “complete syndrome of myxoedema” or “minor thyroid insufficiency”, 7 suggesting that hypothyroidism fell into two clearly defined syndromes.
The concept of mild and severe versions of one condition is well represented in medicine. Functional changes often precede severe changes. Adrenal exhaustion or hypo-adrenalism can precede Addisons Disease, and functional hypoglycaemia can precede late onset diabetes.
In many early stage functional health disorders, the symptoms may be well established, but the laboratory evidence and blood changes are not always present. This is not surprising, as many ‘normal’ ranges for blood tests are designed to identify only major changes in the organs or systems under test.
Higgins in 1925 drew attention to skin changes, constipation, headaches and general nervousness as symptoms of incipient hypothyroidism, 8 while in 1929 McLester discussed the general poor health and decreased metabolic rate that accompanied poor thyroid function. 9
In 1933 Mayo observed complications in the circulation, and the typical subnormal temperatures that occur when the metabolism is depressed. 10 Breckenridge in 1932, 11 Hinton in 1933 12 and Salzman in 1916 all reported that hypothyroidism was a cause of menorrhagia (heavy periods).13
Raised cholesterol levels were noted in thyroid patients by many investigators. This was found so predictably that measuring the serum cholesterol was seen as a potentially useful method to assess thyroid function and to monitor changes in the symptoms following thyroid treatment.
In 1934 Hurxthal concluded that “the relationship between the blood cholesterol and the basal metabolism is usually reciprocal, when they undergo change as a result of variations in the activity of their thyroid gland”. Also, “the blood cholesterol provides another variable which may be used as a guide in the treatment of thyroid disease”. 14