Hyperthyroidism resident survival guide
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Pervaiz Laghari, MD[2]
Overview
Most patients with severe hyperthyroidism present with a dramatic symptom constellation. Hyperthyroidism's typical symptoms include palpitations,heat intolerance,, increased bowel movement frequency tremor, anxiety, weight loss despite normal or increased appetite, and shortness of breath.Goiter is commonly found on physical examination.
SPECIFIC ORGAN SYSTEMS
| Skin | Sweating,Onycholysis,Hyperpigmentation,Thinning of the hair |
| Eyes | Stare and lid lag, ophthalmopathy. |
| Cardiovascular | Heart rate is increased,Systolic hypertension ,pulse pressure is widened, congestive heart failure, Atrial fibrillation |
| Gastrointestinal | Weight loss,hyperphagia,hyperdefecation and malabsorption |
| Respiratory | Dyspnea, tracheal obstruction, exacerbate underlying asthma,Pulmonary arterial systolic pressure is increased |
| Neuropsychiatric | Anxiety, tremor, restlessness, irritability,insomnia,psychosis, agitation,depression, seizures |
| Genitourinary | Urinary frequency and nocturia |
| Hematologic | normochromic, normocytic anemia |
| Neck | Thymic enlargement |
| Bone | osteoporosis and an increased fracture risk |
Causes
Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated.
Common Causes
Diagnosis
Serum TSH measurement has the highest sensitivity and specificity of any single blood test used in the evaluation of suspected thyrotoxicosis and should be used as an ini-tial screening test . However, when thyrotoxicosis is strongly suspected, diagnostic accuracy improves when aserum TSH, free T4, and total T3 are assessed at the initial evaluation. Serum TSH levels are considerably more sensitive than direct thyroid hormone measurements for assessing thyroid hormone excess. In overt hyperthyroidism, serum free T4,T3,or both are elevated, and serum TSH is subnormal (usually<0.01mU/L ina third-generation assay). In mild hyperthyroidism, serum T4 and free T4 can be normal, only serum T3 may be elevated, and serum TSH will be low or undetectable
| Check TSH level | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| High TSH | Low TSH | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| High Free T4 | High Free T4 | Normal Free T4 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Secondary hyperthyroidism | Primary hyperthyroidism | Subclinical hyperthyroidism | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Pituitary imaging | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Treatment
For patients with clinical features of thyroid storm,we start immediate treatment with a beta blocker And then either 200 mg of propylthiouracil (PTU) every four hours or methimazole (orally 20 mg every four to six hours). PTU is preferred over methimazole due to the effect of PTU to decrease the conversion from T4 to T3. Iodine administration should be postponed for at least one hour after administration of thionamide to prevent the iodine from being used as a substrate for new hormone synthesis. We also administer glucocorticoids (hydrocortisone, 100 mg intravenously every eight hours) in patients with thyroid storm clinical features.Supporting therapy and the detection and treatment of any precipitating factors ( e.g. infection) in addition to specific thyroid therapy can be vital to the eventual outcome.The infection needs to be detected and treated, and the aggressive correction of hyperpyrexia is required. Acetaminophen should be used instead of aspirin, as the latter will increase concentrations of serum-free T4 and T3 by interfering with protein binding.
Once clinical improvement is shown, iodine therapy may be discontinued and glucocorticoids may be tapered and discontinued.Beta blockers can be stopped but only after the tests on thyroid function have returned to normal.To maintain the euthyroidism, the dosage of thionamides should be titrated. PTU should be changed to methimazole due to the improved safety profile of methimazole and higher compliance rates.
| Beta blocker | Control the symptoms and signs
|
| Thionamide | Block new hormone synthesis |
| Iodine | Block the release of thyroid hormone |
| Glucocorticoids | Reduce T4-to-T3 conversion, promote vasomotor stability, possibly reduce the autoimmune process in Graves' disease, and possibly treat an associated relative adrenal insufficiency |
Do's
- The content in this section is in bullet points.
Don'ts
- The content in this section is in bullet points.