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Myxedema

Sms & Sns of hypothyroidism differ in relation to the deficient amount of thyroid hormone & rate acuteness deficiency appears.

 

Myxedema

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Sms & Sns of hypothyroidism differ in relation to the deficient amount of thyroid hormone & rate acuteness deficiency appears. Several manifestations of hypothyroidism reflect the lack of thyroid hormone in two ways:

(1)  Global 👉slowing of metabolic activity &

(2)  Accumulated 👉 glycosaminoglycans in interstitial space of systemic organs.

Other Sms & Sns include depression, diminished hearing, diastolic HT, & pleural & pericardial effusions. Clinical picture of central hypothyroidism is like that of primary hypothyroidism. If hypothyroidism induced by hypothalamic-pituitary lesions, manifestations of associated endocrine deficiency e.g., hypogonadism & adrenal insufficiency can mask that of hypothyroidism. Multiple metabolic alterations including hyponatremia, hyperlipidemia, anemia, & high muscle enzymes.  Diminished clearance of: anti-seizures, anti-coagulants, hypnotic, & opioids drugs can be also observed.

Kidney affection: 👉 Reversible rise in SCr observed in 20-90 % of hypothyroid ptns.

 

Treatment of primary hypothyroidism in adults

 

Frank primary hypothyroidism is characterizing by high TSH (thyroid-stimulating hormone) + Low free thyroxine (T4). Overt primary hypothyroidism needs ttt, regardless of Sms, unless it’s transient (as after painless thyroiditis or subacute thyroiditis) or reversible. Target of therapy:

(1)  Alleviation of Sms,

(2)  Normalized TSH,

(3)  Decreasing goitre size (if present), &

(4)  Avoiding over-ttt (iatrogenic thyrotoxicosis). 💣

We aim to keep serum TSH within the normal reference range (about 0.5-5.0 mU/L). It is crucial to notice that there’s an age-related shift towards elevated TSH in elderly, with its upper normal limit = 7.5 mU/L in 80 y. olds.  

 

Ttt of choice to correct hypothyroidism is synthetic thyroxine (T4, levothyroxine). For most ptns, it is better not to combine T4-triiodothyronine (T3) in therapy. However, T4-T3 therapy may improve Sms in certain ptns (e.g., post-thyroidectomy or ablation with radioiodine). Combined therapy is discouraged with the following:

(1)  Elderly.

(2)  Pregnant women.  

(3)  CVS disorders (excess T3 can induce arrhythmia).

If T4-T3 therapy is used, T4-to-T3 ratio should be about 13:1 to 16:1.  Remaining on the same formula of T4 is advised. Either a generic or a brand-name formula is accepted. With switching from one manufacturer to the other, we should measure TSH 6 wks after shifting the preparations to maintain TSH within its therapeutic level.  

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Initially, full dose (1.6 mcg/kg/d) in young, healthy ptns, but older ptns & CAD ptns should commence at a lower dose (25-50 mcg/d). T4 must be given on empty stomach, ideally 30-60 min before breakfast. After commencing T4 therapy, ptn should be re-evaluated & TSH should be re-measured in 6 wks with dose adjustment accordingly. Sms may start to resolve after 2-3 wks, but steady-state TSH will not reached before at least 6 wks.  If ptn showing hypothyroid Sms & TSH is confirmed by frequent testing to be at the upper limit or above the reference level, it’s accepted to increment the dose & to aim for TSH in its lower ½ of normal range; however, improved Sms with higher doses may rely on expectation rather than true physiologic benefit.

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