the patient had gained 11 kg over three years despite reducing her food intake. She had been told she was depressed, deconditioned, and eating too much. A single thyroid blood test at Mascot Healthcare found her TSH at 18.2 — more than 10 times the upper limit of normal. Levothyroxine treatment transformed her within 8 weeks.
Office manager. 3-year history of progressive weight gain (11 kg), fatigue, cold intolerance, constipation, dry skin, and low mood. Had been investigated for depression and told to "eat less." TSH: 18.2 mIU/L (severely elevated). Free T4: 7.1 pmol/L (low). Hypothyroidism confirmed.
Thyroid Function Test (TSH + T4)the patient had gained weight steadily from age 34. She had seen a doctor who had recommended "more exercise and less carbohydrates." She had tried. The weight continued to increase. She had seen a second doctor who had suggested depression — she was prescribed sertraline. Her mood did not improve significantly. She had started to believe that this was simply who she was now.
A colleague who was a nurse had observed her closely over several months. "Amaka, your skin is very dry — look at your elbows. And you're always cold even when we're sweating. Have you checked your thyroid?" the patient had not. She came to Mascot Healthcare. The doctor ordered a TSH and free T4.
The TSH result: 18.2 mIU/L. The doctor called her immediately. "Your thyroid is severely underactive," she said. "Everything you've been experiencing — the weight gain, the fatigue, the cold sensitivity, the constipation, the low mood — these are all symptoms of hypothyroidism. And they are completely reversible with treatment."
The thyroid gland controls metabolic rate, temperature regulation, mood, and energy production. TSH (thyroid-stimulating hormone) from the pituitary is the most sensitive indicator — a high TSH means the pituitary is working hard to stimulate an underperforming thyroid.
The most sensitive test. High TSH = underactive thyroid (hypothyroidism). Low TSH = overactive thyroid (hyperthyroidism). Normal: 0.4–4.0 mIU/L. the patient's: 18.2.
The main thyroid hormone. Low T4 with high TSH confirms primary hypothyroidism. Normal: 12–22 pmol/L. the patient's: 7.1.
Active thyroid hormone. Measured if hyperthyroidism or T4-to-T3 conversion issues are suspected.
Thyroid peroxidase antibodies — positive in Hashimoto's thyroiditis (autoimmune hypothyroidism), the most common cause of underactive thyroid.
Positive in Graves' disease — the most common cause of hyperthyroidism. Helps distinguish Graves' from other causes.
Hypothyroidism is estimated to affect 2–5% of women globally — with higher rates in women of African descent. Its symptoms — weight gain, fatigue, depression, constipation, dry skin, cold intolerance — are non-specific and commonly attributed to lifestyle, ageing, stress, or mental health conditions.
A TSH test costs and takes 24 hours. Every one of the patient's symptoms could have been attributed to her thyroid from the first visit. Three years of weight gain, low mood, and self-blame would have been prevented by a single blood test.
Thyroid hormone replacement was started — the standard treatment for an underactive thyroid. The starting dose was selected conservatively given her age and symptom duration, then increased at 6 weeks based on repeat TSH (8.4 mIU/L — improving but not yet at target). Target TSH: 0.5–2.5 mIU/L.
At 8 weeks, the patient described the change: "I feel like the lights came back on." Her energy had returned. She was warm again. Her bowels were normal. Her skin was moisturising from within. Her mood — for the first time in three years — felt like her own.
The antidepressant prescribed at a previous clinic was gradually tapered and discontinued — her depression had been a symptom of hypothyroidism, not an independent condition. TPO antibodies were positive: confirming Hashimoto's thyroiditis as the underlying cause.
TSH 18.2, FT4 7.1 — severe primary hypothyroidism. TPO antibodies positive: Hashimoto's thyroiditis. Levothyroxine started and uptitrated.
Thyroid hormone replacement (dose increased at 6 weeks); repeat TSH at 6 weeks then 3 months then annually; antidepressant tapered; dietary iodine advice.
TSH at 6 weeks: 8.4 mIU/L (improving). TSH at 3 months: 1.8 mIU/L (target range). Weight: 4 kg lost. Mood: significantly improved. Repeat annually.
the patient's TSH normalised at 3 months. She lost 5 kg in 4 months without dietary change. She discontinued the antidepressant without relapse. She describes the thyroid diagnosis as "finding the real reason for 3 years of suffering."
Unexplained weight gain, fatigue, and depression that does not respond to treatment should prompt a TSH test — especially in women aged 30–60. A TSH test costs. Three years of wrong treatment — including an antidepressant for a thyroid problem — could have been prevented.
Hypothyroidism is fully treatable with a once-daily tablet. The response is often dramatic — patients describe feeling like themselves again within weeks of starting treatment.
Tired, cold, gaining weight despite eating less, and low in mood? That's a thyroid profile. One blood test. A tablet a day. A complete transformation.
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