Endocrine Flashcards
Thyrotoxicosis - Causes
- Primary
-
Grave’s
- Most Common, younger F:M 10:1
- ABs bind TSH-R and stimulate TSH production/release
- TMN
- Second most common, >50yrs, milder
- Can present acutely if iodine deficient pt receives iodine load
- Toxic adenoma
-
Grave’s
- Thyroiditis
- Painful
- De Quervain syndrome
- Suppurative
- Not painful
- Trauma
- Drug - amio /Li / iodine
- Infection
- Autoimmune
- Radiation
- Subacute / subclinical /
- Painful
- Postpartum thyroiditis
- Exogenous / Factitious
- Secondary (rare)
- Pituitary adenoma, Ectopic/metastatic thryrdoid tissue
Thyrotoxicosis - Eye signs
- Stare
- Exophthalmos
- Lid lag
- Proptosis
- Increased tearing / irritation
- Peri-orbital oedema
- Limited superior gaze
Thyroid Storm Treatment
- ABCs
-
Step 1 - Beta blocker
- Propanolol 0.5-1mg IV q15min
- Sympathetic surge
-
Step 2 - Stop T4 → T3 production
- PTU 500-1000mg PO/NG/PR
- Methimazole 20-30mg
-
Step 3 - Inhibit T3/T4 release
- Potassium iodide 5 drops
- Lugol solution 4-8 drops
- NB only 1 hr after Step 2 (can worsen Sx)
-
Step 4 - Inhibit peripheral T4 → T3 conversion
- Hydrocortisone 300mg IV
- PTU and propanolol also do this
-
Supportive
- ABCs
- ABx
- Cooling /Benzos for agitation / IVF / Glucose
Additional interventions
Cholestyramine
Blocks enterohepatic recirculation of thyroid hormone
Dose: 4 g PO Q6 hours
L-Carnitine
Blocks entry of thyroid hormone into cells
Dose: 1 g PO Q12 hours
Thyroid Storm - Clinical criteria
- Fever
- Tachycardia
- AMS
- CCF
- GI
- Ppt event
Burch-Wartofsky Scale
Score > 45 high likelihood, 25-44 impending, <25 unlikely
Thyroid Storm - precipitants
Untreated / undiagnosed or non-compliant + stressor => thyrois storm
- Systemic - trauma, infection/sepsis, surgery
- Endocrine insult - DKA, HHS
- Drug induced
- CVS - MI, CVA, PE,
- OBS - labour, pre-eclampsia
- Radioactive iodine
Hypothyroidism Causes
Primary causes:
- Idiopathic atrophy (95%) of cases.
- Iatrogenic (ie post radioactive iodine or surgery)
- Congenital, (agenesis)
With goitre (reduced thyroid hormone and elevated TSH):
- Iodine deficiency - commonest cause globally
- Chronic thyroiditis
- Hashimoto’s
- Pregnancy / Post-partum
- Infection
- Surgery
- Trauma
- Radiation
- Drugs
- Iodine / amio / Li
- Non-compliance
Secondary Causes: (rare)
- Pituitary disease
- Hypothalamic disease
Hypothyroid - Bloods
High TSH and Low T4 - primary hypothyroidism
Others
- Mild anaemia
- Hypercholesterolemia
- Elevated hepatic enzyme levels
- Elevated prolactin level
- Hyponatremia secondary to extracellular volume expansion produced by an elevated antidiuretic hormone level
- Blood glucose levels may be normal to low as a result of decreased gluconeogenesis and reduced insulin clearance.
Myxodema Coma - Clinical findings
- Hypothermia
- Hypotension - refractory
- Hypoventilation - T2RF
- Bradycardia
- AMS - lethargy to stupor to coma
- Myxoedema - puffy eyelids, large tongue, broad nose, legs
- Metabolic
- Low Na, glucose
Myxoedema PPt
- Myocardial infarction
- Infection
- Sepsis
- Stroke
- Pulmonary embolism
- Prolonged exposure to cold
- Exposure to drugs that suppress the central nervous system
- DKA
Myxoedema Crisis - Rx
Supportive
- ABC
- IVF
- May need fluid restriction for low Na
- Rx hypogylcaemia
- Hypothermia - passive warming
- IV hydrocortisone 100mg
- Rx underlying ppt
Specific
- Thyroid hormone replacement
- T3 - 20mcg IV or 10mcg IV if old or Hx of CVD/arrhthmia
- T4 - 200-400mcg IV then 75-100mcg daily
Interpreting Thyroid tests
Diabetes diagnostic criteria
- HbA1C >6.5%
- Fasting glucose >7.0mmol/l
- Random glucose >11.1mmol/l AND Sx
- OGT glucose >11.1mmol/l
Serum osmolality
275-295 mOsm/kg
2[Na+] + glucose/18 +BUN/2.8
Estimated
2[Na] + glucose + urea
Corrected Sodium
135-145
[1.6 x (glucose -5.6)] /5.6
Estimated
Na + (glucose -5 /3)
Cerebral Oedema
- High mortality 90%
- Occurs 6-8 hours into correction of hyperglycaemic state
- Consider if
- acute drop in GCS / coma
- Severe headache
- Pupil changes
- BP changes
- Seizures
RF
- First diagnosis
- <5yrs
- Initial pH <7.1 and CO2 <18
- Aggressive IVF
- ? HCO3 infusion
Mx
- Supportive + ABCs
- Head up 30 degrees
- Mannitol 1-2g/kg or 3% saline 5-10ml/kg
- Decrease IVF rate to 1/3
- No role of steroids
- CT head