It's reckoned that around 10 per cent of those who suffer from thyroid dysfunction may have such a slight, subclinical, form of it.
The condition is tricky to diagnose and, often, only a blood test can make a definite diagnosis. Typical symptoms include fatigue, weakness, weight gain or a difficulty in losing weight, coarse, dry hair, hair loss, cold intolerance, muscle cramps, constipation, depression, irritability, memory loss, abnormal menstrual cycles and a low libido.
Once diagnosed, it's simple enough to treat in most cases, and doctors will usually recommend a pill that replenishes T4 levels.
But there's plenty else you can do without going within a mile of an endocrinologist. To find out if you are a sufferer, place a thermometer under your armpit for 10 minutes first thing in the morning. A temperature below the standard range of 36.6-36.8o C (97.8-98.2o F) could be indicative of an underactive thyroid (and anything above that range suggests an overactive one). Supplementing with zinc, and vitamins A and E can help, as can the essential fatty acids. There are also specific alternative remedies that have been proven to overcome the problem (Arch Intern Med, 2005; 165: 2460-6, 2467-72).
* A complete course in treating hypothyroidism naturally is given in WDDTY vol 12 no 9 (Special Report, pages 1-4).