Thyroid Symptomatology across the Spectrum of Hypothyroidism and Impact of Levothyroxine Supplementation in Patients with Severe Primary Hypothyroidism

OBJECTIVE: This study aimed to determine the clinical and biochemical profile of patients with severe primary hypothyroidism (SPH) (TSH ≥40 μIU/ml) as compared to milder forms of hypothyroidism and document improvement in hypothyroidism symptoms in SPH. METHODS: Thyroid symptomatology and biochemistry were evaluated in SPH, non-severe overt primary hypothyroidism (NSOPH; TSH <40 μIU/ml), subclinical hypothyroidism (ScH) and healthy controls. A total of 598 consecutive patients of hypothyroidism were screened of which 461 patients' data were analyzed (91 SPH, 130 NSOPH and 240 ScH). Thyroid symptomatology was re-evaluated at 12 weeks follow-up in SPH following restoration of euthyroidism with levothyroxine. RESULTS: The median (interquartile range) age of patients was 35 (28-42) years with 91.6% female. The commonly noted symptomatology were shortness of breath (93.4%) and fatigueability (91.2%) in SPH, fatigueability (68.46%) and limbs swelling (43.07%) in NSOPH, and fatigueability (56.67%) and shortness of breath (32.92%) in ScH. All symptomatology were significantly higher in SPH. Delayed tendon reflex, carpel tunnel syndrome and meno-metrorrhagia were exclusive in SPH. Occurrence of menstrual irregularities was 73.62%, 28.46% and 16.25% in SPH, NSOPH and ScH, respectively. SPH patients had significantly higher cholesterol and triglycerides. There was significant improvement in symptomatology, reduction in body weight (−2.11 kg), improvement in hemoglobin (+0.64 g/L) with fall in total cholesterol (−18.96%), LDL-cholesterol (−23.46%) and triglycerides (−13.53%) following euthyroidism restoration in subjects with SPH. Common residual symptoms were fatigue (10%), poor memory (8%) and menstrual irregularities (6%). CONCLUSION: Thyroid symptomatology differs significantly across spectrum of hypothyroidism, being significantly worse in SPH. Euthyroidism restoration is associated with reversal of majority of thyroid symptomatology.