Endocrine Flashcards

1
Q

Thyrotoxicosis - Causes

A
  • 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
  • Thyroiditis
    • Painful
      • De Quervain syndrome
      • Suppurative
    • Not painful
      • Trauma
      • Drug - amio /Li / iodine
      • Infection
      • Autoimmune
      • Radiation
      • Subacute / subclinical /
  • Postpartum thyroiditis
  • Exogenous / Factitious
  • Secondary (rare)
    • Pituitary adenoma, Ectopic/metastatic thryrdoid tissue
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2
Q

Thyrotoxicosis - Eye signs

A
  1. Stare
  2. Exophthalmos
  3. Lid lag
  4. Proptosis
  5. Increased tearing / irritation
  6. Peri-orbital oedema
  7. Limited superior gaze
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3
Q

Thyroid Storm Treatment

A
  • 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

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4
Q

Thyroid Storm - Clinical criteria

A
  • Fever
  • Tachycardia
  • AMS
  • CCF
  • GI
  • Ppt event

Burch-Wartofsky Scale

Score > 45 high likelihood, 25-44 impending, <25 unlikely

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5
Q

Thyroid Storm - precipitants

A

Untreated / undiagnosed or non-compliant + stressor => thyrois storm

  1. Systemic - trauma, infection/sepsis, surgery
  2. Endocrine insult - DKA, HHS
  3. Drug induced
  4. CVS - MI, CVA, PE,
  5. OBS - labour, pre-eclampsia
  6. Radioactive iodine
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6
Q

Hypothyroidism Causes

A

Primary causes:

  1. Idiopathic atrophy (95%) of cases.
  2. Iatrogenic (ie post radioactive iodine or surgery)
  3. Congenital, (agenesis)

With goitre (reduced thyroid hormone and elevated TSH):

  1. Iodine deficiency - commonest cause globally
  2. Chronic thyroiditis
    • Hashimoto’s
    • Pregnancy / Post-partum
    • Infection
    • Surgery
    • Trauma
    • Radiation
  3. Drugs
    • Iodine / amio / Li
    • Non-compliance

Secondary Causes: (rare)

  1. Pituitary disease
  2. Hypothalamic disease
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7
Q

Hypothyroid - Bloods

A

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.
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8
Q

Myxodema Coma - Clinical findings

A
  1. Hypothermia
  2. Hypotension - refractory
  3. Hypoventilation - T2RF
  4. Bradycardia
  5. AMS - lethargy to stupor to coma
  6. Myxoedema - puffy eyelids, large tongue, broad nose, legs
  7. Metabolic
    1. Low Na, glucose
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9
Q

Myxoedema PPt

A
  1. Myocardial infarction
  2. Infection
  3. Sepsis
  4. Stroke
  5. Pulmonary embolism
  6. Prolonged exposure to cold
  7. Exposure to drugs that suppress the central nervous system
  8. DKA
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10
Q

Myxoedema Crisis - Rx

A

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
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11
Q

Interpreting Thyroid tests

A
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12
Q

Diabetes diagnostic criteria

A
  1. HbA1C >6.5%
  2. Fasting glucose >7.0mmol/l
  3. Random glucose >11.1mmol/l AND Sx
  4. OGT glucose >11.1mmol/l
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13
Q

Serum osmolality

A

275-295 mOsm/kg

2[Na+] + glucose/18 +BUN/2.8

Estimated

2[Na] + glucose + urea

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14
Q

Corrected Sodium

A

135-145

[1.6 x (glucose -5.6)] /5.6

Estimated

Na + (glucose -5 /3)

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15
Q

Cerebral Oedema

A
  • 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
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16
Q

DKA Mx and Therapeutic End Points

A

Mx

  • Resuscitate
    • Correct hypotension / bradycardia
    • No insulin until K+ >3.3mmol
  • Repair/Replace
    • Volume repletion
      • Fluid deficits >100ml/kg
    • Correct electrolyte imbalances
    • Insulin 0.1unit/kg/hr
    • Rx ppt cause
    • Prevent complications
    • VTE Prevention
  • Reassess
    • Ongoing BSL / ketone / K monitoring
    • Add 5% dextrose when BSL <15mmol
    • K+ replacement
      • > 5.5 - no replacment
      • 4-5.4 - 10mmol /hr
      • <4 - 20mmol /hr
      • <3.3 - stop insulin and replace K+

Therapeutic Goals

  • Ketones 0.5mmol/hr
  • HCO3 - 3mmol/hr
  • BSL - 3mmol/hr
  • K+ - 4-5mmol

Resolution

  • Clinical improvement
  • BSL <11.1
  • Ketones < 0.6
  • VBG pH > 7.3
17
Q

HHS

A
  • Hyperglycaemia >30mmol
    • Ketones <3
    • Acidosis pH>7.3, HCO3 >15
  • Hyperosmolarity >320 mOsm/kg
  • Dehydration
  • AMS

Mx

  • Resuscitate
  • Rx underlying cause
  • IVF
    • Fluid deficit 100-220ml/kg
    • Aim 50% deficit in first 12 hours
      • 0/9% Saline 1l.hr for first few hours
      • If Na corrected(serum osmolality) responding then continue at slower rate
      • If Na corrected high then switch to .45% Saline
  • Electrolyte repletion
    • K / Mg / PO4
    • K+ supplementation as per DKA
  • BSL
    • Insulin 0.1u/kg/hr
    • Lower by 3mmol/hr
    • When BSL <15
      • Insulin 0.05u/kg/hr
      • Dex/Saline
  • ICU/Endocrine
  • VTE prophylaxis
18
Q

DKA vs HHS

A
19
Q

Hypercalcaemia

A

Serum levels >3mmol/l symptomatic

Calc:

Sx: Stones, Bones, Moans, Groans

Signs: ECG - short QT interval

Mx

Excretion

  • IVF
  • LOOP diuretic (thiazide makes worse)
  • Dialyse

Osteoclast inhibition (dec Ca release)

  • Bisphosphonate - Pamidronate 90mg IV
  • Calcitonin - PRN for cardiac dysrhythmias - takes 24-48 hrs to work
20
Q

Adrenal Insufficiency Causes

A

PRIMARY - high ACTH, low cortisol (hence hyperpigmentation)

  • Chronic
    • Autoimmune (Addison’s)
      • Post infectious - HIV, CMV, MAC, TB,
    • Congenital adrenal hyperplasia
    • Post-infectious
    • Metastatic - breast/lung Ca
    • Infiltrative
    • Bilateral adrenalectomy
    • Drugs - rifampicin, etomidate, ketoconazole
  • Acute
    • Haemorrhage /infarction
      • Meningooccaemia (Waterhouse - Friedrichson’s)
      • Anticoagulants
      • Anticardiolipin AB syndrome
      • Trauma

SECONDARY - severe stressor

  • Chronic
    • Pituitary - tumour, surgery
    • Drugs
      • Chronic steroid use
      • MAB therapy
    • Infiltrative - TB, sarcoid, eosinophilic granuloma
  • Acute
    • Pituitary apoplexy
    • Sheehan’s (post-partum pituitary necrosis)
    • TBI
    • Relative - sepsis, hepatic failure, severe pancreatitis, trauma)
21
Q

Hyponatraemia Causes

A

Def

  • ​Na+130 -135 mmol/L - mild
  • ​Na+125 -129 mmol/L - moderate
  • ​Na+< 125 mmol/L - severe
  • AMS, lethargy, confusion => seizures, coma

Causes

  1. Hypovolaemia - dehydration
  2. Water retention - failures - heart, kidney, liver, hypothyroid, psychogenic polydipsia
  3. Salt loss - duiretics
  4. Cerebral Salt wasting
22
Q

SIADH

A

Essential criteria:

  1. Hyponatraemia
  2. Hypotonic - dec serum osmolality < 275mOsm/kg
  3. Urinary Na > 30 mmol/l
  4. Clinical normovolaemia
  5. No failures - cardiac, hepatic, renal
  6. Not drug related

Causes

  1. Tumours
    1. Lung - oat cell. bronchogenic
    2. Blood - leukaemia, lymphoma, thymoma
    3. Pancreatic
  2. Neurologic
    1. Trauma
    2. Infection
    3. GBS
    4. Autoimmune - SLE
    5. AIDS
  3. Pulmonary
    1. Pneumonia, TB, Abscess
    2. PPV
  4. Drugs
    1. Antidepressants - Fluoxetine/Amitriptyline, paroxetin
    2. Carbamazepine

Tests
Low serum osmolality
Urine osmolality > 100mOsm/l (impaired water excretion)

Urine Na > 30mmol/l

23
Q

Urine vs Serum osmolality

A

In context of hyponatraemia:

Serum osmolality - if > 280 mosm/kg indicates spurious causes

  • ​hyperproteinaemia / hyperlipidaemia
  • ​hyperglycaemia / methanol / mannitol

Urine osmolality

•​if serum hypo-osmolality confirmed +

Urine osmlolality < 100 mosm/kg

  • ​ complete and appropriate suppression of ADH
  • ​causes
  • ​primary polydipsia
  • ​reset osmostat syndrome

Urine osmolality > 100 mosm/kg

  • ​indicates impaired water excretion
  • ​causes
  • ​hypothyroidism
  • ​adrenocortical insufficiency
  • ​hypovolaemia
  • ​renal /hepatic / cardiac failure
  • ​SIAD

Urinary Na+

  • ​ < 20 mmol/L usually indicates hypovolaemia
  • ​> 30 mmol/L is suggestive of SIADH
24
Q

Sodium Correction

A

Seek and treat underlying cause

Euvolaemia - fluid restrict

Hypovolaemia - Volume replacement IV saline

3% Saline for treatment/prevention seizures

Consider loop diuretic to increase free water loss

Na correction

Acute hyponatraemia or chronic severe - rapid correction

•​Na < 115

  • ​increase [Na+] 5-8mml/L in 30-60min.
  • ​then increase [Na+] 5-8 mmol/L each day for next 48-72 hours

•​Na > 115

-​aim to increase 5-8mmol/L each day for 48-72 hours

Sodium dose

•​amount of Na+necessary to raise the serum [Na+] to 125 mmol/L approximated by

Na = (125-Na) X TBW x 0.6

•​where Na+ is in mmol/L, TBW is total body water in (L) = body weight x 0.6

25
Q

Phaeochromocytoma

A

Rare neoplams of adrenal medulla (90%) or SNS (10%)
Rare cause secondary HTN

Clinical features of xs catecholamines
Episodic - HA, sweating, pallor, flushing, tachycardia / palpitations
HTN / OH
CNS - anxiety
GIT - N/V/ wt loss

Ix
Metanephrine levels
24 urinary catecholamines / VMA
Imaging - CT /MRI

Mx
Alpha blockade prior to BB
- Prazocin 1-2mg PO or phentolamine IV 5mg
- BB - Labetalol / propanolol
- Endocrine / surgical / oncology referral