Question 14

Regarding thyroid dysfunction in critically ill patients:

a)    List the likely clinical and laboratory findings that are seen in a patient with severe hypothyroidism, that requires ICU management.    (25% marks)

b)    Outline your approach to managing this patient in a).
(40% marks)

c)    List the laboratory findings in ‘euthyroid sick’ syndrome (ESS) in a critically ill patient.
(20% marks)

d)    Outline your approach to managing a patient with ESS in the ICU.
(15% marks)
 

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College answer

Not available.

Discussion

It's difficult not to introduce false subtext into the exam stems, as this is a high-stakes piece of text, and people will surely scrutinise each letter as carefully as Biblical scholars, inflating the meaning of seemingly random choices of wording and grammar. For example, "list the likely clinical and laboratory findings" leaves the reader to wonder how many findings such a list ought to contain.  These should be findings "that are seen in a patient with severe hypothyroidism, that requires ICU management", presumably implying that one should not list findings seen in relatively healthy community-based outpatients with hypothyroidism (and the comma in the middle is suspicious). And then, we are invited to "outline your approach to managing this patient in a)", but..... there is no specific patient case mentioned in a), only "a patient with severe hypothyroidism, that requires ICU management". What mysterious grade items lurk in the difference between this wording, and simply asking the candidates to "otline your approach to managing a patient with severe hypothyroidism in the ICU"?

Pushing down the paralysing fear that one completely misinterpreted the question, the following potential answer can be offered:

a) Clinical and laboratory findings in severe hypothyroidism: left without instructions regarding how many of these were required, the author has listed all of them; though one might make the argument that postural dizziness  amenorrhoea and decreased libido are unlikely to be important in a patient that requires ICU management, and could have been omitted.

  • Symptoms
    • Lethargy
    • Depression
    • Psychosis
    • Decreased level of consciousness
    • Cold intolerance
    • Dry skin
    • Hoarse voice
    • Neck swelling (goitre)
    • Postural dizzyness
    • Gastro-oesophageal reflux
    • Constipation
    • Myalgia
    • Amenorrhoea
    • Decreased libido
  • Signs

    • Hair loss
    • Loss of the lateral eyebrows (Queen Anne sign)
    • Dry thickened skin
    • Oedema (usually, non-pitting)
    • Proximal muscle weakness
    • Periorbital oedema
    • Enlarged tongue
    • Bradycardia
    • Pericardial effusion
    • Hypothermia
    • Delayed reflexes
  • Laboratory features

    • Decreased T4 and T3
    • Increased TSH
    • Hyperlipidaemia
    • Hyponatremia
    • Normochromic normocytic anaemia

b) An approach to the management of the severely hypothyroid patient: for 40% of the total mark, this should have been a relatively thick paragraph or point-form list. What follows is a management plan for a patient with a very severe ICU-level hypothyroidism, bordering on myxoedema coma:

  • Specific management:
    • Replace thyroxine.   
      • Initially, IV triiodothyronine 10mcg 8-hourly
      • Also large loading dose (300-500 mcg per day) of enteral thyroxine
      • Decrease to 200mcg/day as the symptoms improve
      • Monitor TSH and clinical response
    • Add corticosteroids (stress dose of hydrocortisone, 50mg 8-hourly)
  • Supportive management:
    • Intubate and ventilate if unconscious 
    • Vasopressors and inotropes (expecting catecholamine resistance)
    • Gentle sedation (expecting increased sensitivity to anaesthetics)
    • Correct hyponatremia
    • Correct hypoglycaemia
    • Watch for bleeding (increased rate of fibrinolysis)

c) Features of sick euthyroid: 

  • T3: low
  • rT3: high
  • T3/rT3 ratio: low
  • T4: high ...or normal
  • TSH: high ...or normal

The sick euthyroid syndrome is a biochemical pattern of decreased circulating T3 levels, without a strong compensatory TSH response. The raised levels of rT3 result in a disproportionate degree of thyroid dysfunction, as rT3 is an inactive form, and therefore a competitive antagonist of "real" T3.

d) Management of sick euthyroid syndrome, in 90 seconds, 

  • There is no benefit in routinely supplementing T3 or T4
  • Focus on the management of the underlying critical illness
  • Correct malnutrition (euthyroid sick syndrome is strongly associated with malnutrition and hypercatabolic states)
  • Use IV triiodothyronine to support patients who have euthyroid sick syndrome and some degree of heart failure or cardiogenic shock

References

Farwell, Alan P. "Nonthyroidal illness syndrome." Current Opinion in Endocrinology, Diabetes and Obesity 20.5 (2013): 478-484.

De Groot, Leslie J. "Dangerous dogmas in medicine: the nonthyroidal illness syndrome." The Journal of Clinical Endocrinology & Metabolism 84.1 (1999): 151-164.

Ringel, Matthew D. "Management of hypothyroidism and hyperthyroidism in the intensive care unit." Critical care clinics 17.1 (2001): 59-74.

Almandoz, Jaime P., and Hossein Gharib. "Hypothyroidism: etiology, diagnosis, and management." Medical Clinics of North America 96.2 (2012): 203-221.