Endocrinology Flashcards
what is hypothyroidism?
what are the hormone levels in primary and secondary?
Decreased levels of circulating thyroid hormones T3 and T4 due to thyroid underactivity
Primary- low T3/T4 and high TSH (raised TSH due to pituitary gland trying to stimulate thyroid (thyroid gland dysfunction) gland to make more T3/T4)
Secondary- low TSH and T3/T4 (low TSH as there is a fault with the pituitary gland/ hypothalamus results in deficiency of TSH)
causes of primary and secondary hypothyroidism?
Primary causes:
Majority are autoimmune
Hashimoto thyroiditis
Atrophic thyroiditis
Secondary causes:
Thyroidectomy/ ablations
TSH deficiency
Congenital
Iodine deficiency
investigations for hypothyroidism?
History and thyroid exam
Bloods- FBC, U&E, LFT, calcium, potassium
TFT- high TSH but low T3/T4
Thyroid peroxidase antibodies- TPO
CK levels
Cholesterol- hypercholesteremia
Short Synacthen test
ECG- pericardial effusion
CXR- pericardial effusion
management of primary and secondary hypothyroidism?
Primary
50mcg Levothyroxine: form of T4 (start at a lower does for 65+ with IHD)
Annual blood test to assess TSH and ensure correct dose of levothyroxine
Avoid T3 and T4 management together
Secondary
Levothyroxine + addressing underlaying cause
Due to failure of pituitary gland itself TSH replacement cannot be used and TSH production is the problem
complications of hypothyroidism?
Goitre
Heart disease- low levels of thyroxine -> high levels of cholesterol
Infertility
Birth defects in babies who’s mother is hypothyroid.
define hyperthyroidism and the hormone levels?
Elevated levels of thyroid hormones (T3/T4) due to thyroid gland overactivity
Low TSH
High T3/T4
causes of hyperthyroidism?
- Grave’s disease- autoimmune 80%
- Nodular goitre (benign nodules within thyroid secreting T3/T4)
- Thyroiditis- inflammation of thyroid commonly after pregnancy or via biologic/ cancer meds (TRAbs -ve)
investigations for hyperthyroidism?
- Bloods- TFT (low TSH, high T3/T4)
- Autoantibodies- TPOAb/ TSH-receptor stimulating Abs
- Radioisotope screening- increased uptake of iodine in Grave’s
- Thyroid US
- US/ CT (nodular goitre)
- ECG- if AF
symptoms of hyperthyroidism?
Weight loss
Diarrhoea + frequent
Heat intolerance
Nervousness
Sweating
Palpitations
Tremor
management of hyperthyroidism?
- propranolol + carbimazole
Carbimazole (block and replace)- high does to completely block action of thyroid with carbimazole and replace thyroid hormones with thyroxine
- Stop at 18 months and reassess
If relapse -> radioactive iodine -> thyroidectomy
If euthyroid -> may be treated but may later develop hypothyroidism - Nodular goitre- BB-blocker -> carbimazole -> radioactive iodine
- Thyroiditis- BB-blocker -> usually resolves on its own/ post-pregnancy or when meds stopped
complications of hyperthyroidism?
Thyroid storm
AF
Eye problems
Cardiac problems
what is a thyroid storm?
symptoms?
treatment?
Medical emergency that requires immediate attention. Underlaying cause of Grave’s disease. can be caused by poor medication compliance. 30-50% mortality
Symptoms:
* Hyperpyrexia
* Altered mental state
* N&V + diarrhoea
* Tachycardia/ AF
Treatment: hydration + cooling -> BB-blockers (propranolol) -> anti-thyroid agent (propylthiouracil) -> iodine solution 4hrs after anti-thyroid agent
what is grave’s disease?
causes?
Autoimmune condition causes hyperthyroidism due to thyroid gland overactivity and release of excess of T3/T4. Confirmed by presence of thyroid-receptor Abs
- Autoimmune condition cause by activity against the TSH receptor
- Men > women
- > if Addisons disease, T1DM, vitiligo
investigations for grave’s disease?
- Bloods- thyroid receptor Abs, FBC, U%E, LFT,
- TFT- high T3/T4 low TSH
- Radio-iodine uptake scans- thyroid activity regions
- Fine-needle aspiration
- ECG- AF
management for grave’s disease?
- Carbimazole + propranolol
Block and replace (carbimazole + thyroxine)
Titration (titrating drug does until lowest possible dose of drugs achieves euthyroid status) - Radioactive iodine
Can be used in refractory grave’s post initial treatment (may cause hypothyroidism) - Surgery- thyroidectomy