Thyroid + parathyroid Flashcards
Causes of Hypothyroidism
(1. ) Hashimoto’s thyroiditis (most common): AI destruction of thyroid, initially presents with hyperthyroid syx e.g. goitre and then hypothyroid syx. RF: women, T1DM, coeliacs
(2. ) Iodine deficiency (most common in developing world)
(3. ) Hyperthyroidism Rx – carbimazole, propylthiouracil, radioactive iodine, thyroid surgery.
(4. ) Medications - Lithium (inhibits TH production), amiodarone,
(5. ) Secondary causes - pituitary or hypothalamus disorder e.g. tumours or radiation
Presentation + Ix of hypothyroidism
- Wt gain
- Cold intolerance
- Fatigue
- Dry skin, brittle nails, coarse hair or hair loss
- Amenorrhoea or menorrhagia
- Reduced memory/cognitions
- Constipation
- Carpal tunnel syndrome
- Hashimoto’s: Painless goitre / hoarseness/ dysphagia
- Secondary hypothyroidism: Recurrent headache, diplopia, visual field defects etc
Ix
(1. ) Bloods: FBC, UE, LFT, TFT
- Primary = TSH (high), T3, 4 (low)
- Secondary = TSH (low), T3, 4 (low)
(2. ) Anti-TPO, Anti-Tg for Hashimoto’s
(3. ) USS neck if goitre/nodules present in adults with normal TFT
Mx of hypothyroidism
Referral for:
- Emergency admission: myxoedema coma (hypothermia, reduced consciousness, hypoglycaemia. Precipitants = infection, MI, stroke, trauma)
- Urgent Endocrinologist: if secondary hypothyroidism
Medical Mx: PO levothyroxine (synthetic T4)
- <50y 50-100mcg/day
- > 50y, CVD - 25mcg/day
- Dose are titrated until TSH levels are normal
- Note: iron, calcium carbonate can interfere with absorption
Causes of Hyperthyroidism
(1.) Thyrotoxicosis = abnormal and excessive quantity of thyroid hormone, can be due to anything e.g. amiodarone
(2. ) Primary hyperthyroidism
- Graves (most common cause)
- Toxic modular goitre
(3. ) Secondary hyperthyroidism e.g. pituitary adenoma
(4. ) De Quervain’s Thyroiditis = Self-limiting hyperthyroidism due to a viral infection
(5. ) Others (hi bHCG): Hyperemesis gravidarum, Molar pregnancy
Presentation of Hyperthyroidism
- Anxiety + irritability
- Heat intolerance
- Wt loss
- Sweating
- Tremor
- Tachycardia
- Diarrhoea
Graves syx: Thyroid eye disease: - Exophthalmos/proptosis - bulging of eye from socket - Eyelid retraction - Lid lag - Pretibial myxoedema (discoloured waxy oedematous) - Thyroid acropachy (clubbing) - Diffuse goitre without any nodules
Toxic multinodular goitre:
- Goitre = firm nodules
De Quervain’s Thyroiditis: Fever, neck pain, dysphagia
Ix of Hyperthyroidism
(1. ) TFT
- Low TSH, high T3,4 = primary
- High TSH, high T3,4 = secondary
- Low TSH, normal T3, 4 = subclinical
(2. ) TSH-receptor antibodies - If graves
(3. ) USS neck – if goitre/nodules + normal TFT
Mx of Hyperthyrdoisim
Referral
- Emergency admission – thyroid storm
- Urgent endo – secondary hyper
- Endo – persistent subclinical hyper
Medical Mx
(1. ) Carbimazole (1st line) or Propylthiouracil (2nd line)
- Dose Titration: taper dose over time, started at 40mg and then gradually reduced
- Block + Replace – carbimazole + levothyroxine
(2. ) OR Radioactive iodine
- Radiation destroys portion of thyroid gland
- For pts who have relapsed after medical mx
- Not allowed to be pregnant for 6m, avoid contact with children + pregnant women
(3.) Propranolol - for adrenaline related syx such as sweating/anxiety/tachycardiac/tremor
(4. ) Surgery: Removed nodules or thyroid gland
- Post-thyroidectomy requires levothyroxine
- Risk: hypoparathyroidism, recurrent laryngeal nerve damage
Thyroid storm - Syx, Mx
Life-threatening complication of hyperthyroidism. Precipitating events: surgery, trauma, infection, iodine load e.g. CT contrast
Syx: Fever, Tachycardia, Confusion + agitation, N+V.
Signs: goitre, thyroid bruit
Management
(1. ) Syx control
- IV propranolol or digoxin (BB CI: asthma, low BP)
- Paracetamol
- Fluids if dehydrated
(2. ) Reduce thyroid activity
- Propylthiouracil
- Lugol’s iodine 4hrs later
- IV hydrocortisone
(3.) Rx of underlying cause
Red flags for thyroid cancer + Ix + Mx
2ww if unexplained thyroid lump
- FH of thyroid cancer.
- Prev irradiation or exposure to high environmental radiation.
- A child with a thyroid nodule.
- Unexplained hoarseness or stridor associated with goitre.
- A painless thyroid mass enlarging rapidly over a period of a few weeks.
- Palpable cervical lymphadenopathy.
- Insidious or persistent pain lasting for several weeks.
Investigation
- Bloods: FBC, UE, LFT, TFT, serum calcitonin, CRP
- USS + biopsy
- CT/MRI
Management
- Total thyroidectomy - >4cm diameter
- Radioiodine ablation/therapy
What is the effect of PTH
PTH regulated ca via:
- Bone: Inc bone resorption (bone releases Ca)
- Kidney: Inc Ca reabsorption, dec PO reabsorption, activates vit D
- Gut: Inc Ca absorption via activated vit D
Causes of Hypoparathyroidism
characterised by hypocalcaemia, hyperphosphataemia and low or inappropriately normal levels of PTH
(1. ) Neck surgery: Thyroidectomy/Parathyroidectomy/laryngeal/oesophageal etc
(2. ) Radiation/drugs
(3. ) Mg
- deficiency – chronic alcoholism, burns
- excess – mg used in preterm labour or preeclampsia
(4. ) Genetic conditions
- DiGeorge syndrome
- Autosomal dominant hypoparathyroidism
- Pseudohypoparathyroidism Type 1A (Albright hereditary osteodystrophy)
Presentation of Hypoparathyroidism
Hypocalcaemia syx
- Tetany: muscle twitching, cramping, spasm
- Chvostek sign
- Trousseau’s sign
- Paraesthesia (fingertips/perioral)
- Prolongs QT interval
Other syx to consider
- Cataracts
- Dental abnormalities
- Brittle nails
Severe hypocalcaemia + hyperphosphatemia
- Seizure
- Arrythmias
Ix + Mx of Hypoparathyroidism
(1. ) Bloods, to r/o other causes of hypocalcaemia
- Ca, PO, PTH, ALP - Lo Ca, Hi PO, lo PTH, normal ALP
- UE – r/o CKD
- Vit D – r/o vit D deficiency
(2.) ECG
Mx
- Urgent IV calcium gluconate if severe hypocalcaemia syx e.g. tetany
- Diet rich in diary, Ca, Vit D
- Ca, vit D3, PTH supps
Causes of hypocalcaemia
(1. ) vitamin D deficiency - malnutrition, malabsorption
(2. ) CKD - Damage to kidney, poor Ca reabsorption, less vit D
(3. ) hypoparathyroidism: parathyroidectomy, pseudohypoparathyroidism
(4. ) Hyperphosphatemia
- tissue injury e.g. rhabdomyolysis/burns
(5. ) Large blood transfusion
(6. ) Acute pancreatitis
Ix + Mx of hypocalcaemia
(1.) ECG
(2. ) Bloods: Ca, Phosphate, Albumin, Total protein, ALP, PTH, Mg, Vit D, Amylase, UE, CK
- Note: remove tourniquet before taking blood sample for Ca
Management
Acute Mx e.g. sever hypo syx: tetany, seizures
- IV Ca gluconate 10ml of 10% soln over 10mins if severe syx
- ECG monitoring
- Rx of underlying cause
Long term Mx
- Treat cause
- Encourage good dietary calcium and Vitamin D intake or consider supps
- Alphacalciferol if CKD
- Mg supp if concurrent hypomagnesaemia
