HYPOTHYROIDISM-INVESTIGATIONS

SUMMARY

1. High TSH (> 10 mU/L) + low free T₄ ⟹ primary (thyroid) hypothyroidism.

2. High TSH (5-10 mU/L) + normal free T₄ ⟹ subclinical hypothyroidism. TSH drifts up as we age & gain weight. Patients with TSH 5-10mU/L will develop hypothyroidism at the rate of 4%/year. Risks: family hx of autoimmune thyroid disease & anti-TPO Ab.

3. Low/normal TSH + low free T₄ ⟹ secondary (pituitary)/tertiary (hypothalamus) hypothyroidism. assoc. with deficiency of multiple hormones. Image the sella.

OTHER ABNORMALITIES
4. Hyponatremia
5. Normochrmic/normocytic anemai
6. Hyperlipidemia
7. Pericardial effusions on echo

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].