- Severe hypothyroidism characterized by 1) decrease mental status 2) hypothermia
Why should I know?
- endocrine emergency which remains a clinical diagnosis
- mortality rate 30-40%
- treat based on suspicion without delay for laboratory confirmation.
- CNS: confusion, lethargy, psychosis (myxoedema madness), seizures, slow ankle reflexes.
- Hypothermia: impaired thermogenesis
- Hyponatremia: renal impairment, SIADH
- renal impairment: hypothyroidism cause increase peripheral vascular resistance and reduce GFR, reduce water excretion, cause dilution hyponatremia. proposed
- SIADH: hypothyroidism cause decrease cardiac output and hypovolemia then lead to baroreceptor-mediated ADH release. debating
- Hypoventilation with respiratory acidosis, due to depression of central ventilatory drive.
- Hypoglycemia: due to decrease gluconeogenesis and associated adrenal insufficiency.
- CVS: bradycardia, heart failure (elevated jugular venous pressure, pedal edema, S3), pericardial effusion (muffled heart sound), hypotension.
- Weight gain
- Voice change
- Skin: puffy face, carotinemia
- thyroidectomy scar
- Acute myocardial infarction
- Cold exposure
- sedative drug; opiates & BZD
Long standing hypothyroidism:
- surgery or radio iodine therapy
- medication: amiodarone, lithium
- autoimmune thyroiditis
- RP -hyponatremia
- CK – >1000iu/L -hypothyroid cause myopathy
- ABG: type 2 failure cause by hypoventilation
- Serum cortisol: look for associated hypocortisolism
- CXR: cardiomegaly, pleural effusion, pulmonary edema, penumonia
- ECG: MI, bradycardia, J waves (hypothermia), low voltage QRS complexes (in pericardial effussion)
Figure: J waves: causes of J waves ; Hypothermia, Brugada Syndrome, BER, Hypercalcemia
- Fluid resuscitation if hypotension. add vasopressor if not respond to fluids. avoid hypotonic fluid in hyponatremia.
- rewarm passively, with blanket.
- IV Hydrocortisone 100mh TDS (associated hypocortisolism, stop if serum cortisol normal).
- Hypoglycemia, treat with IVD D10%
- Hyponatremia, correct slowly with normal saline
- Cardiac failure: diuretics, vasodilator
- Sepsis: Antibiotic
- Thyroid hormone replacement theraphy
- IV or oral
- T3 (triiodothyronine- advantage: rapid onset, greater biological activity) or T4 (L-thyroxine)
- T3: 2.5 ug TDS, double dose every 2-3 days, target 30-40 ug/day
- T4: 25 ug as test dose, then increase to 500 ug/day on 1st day. subsequent dose 25-100 ug/day.
- maintenance dose should be lower in elderly and ischemic heart disease.