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Adrenal insufficiency-diagnosis

Last author update: 6 April 2022
Last staff update: 6 April 2022

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PubMed Search: Adrenal insufficiency [TI] chemistry full text [SB]

Sarrah Lahorewala, B.D.S., Ph.D.
Roger L. Bertholf, Ph.D.
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Cite this page: Lahorewala S, Bertholf RL. Adrenal insufficiency-diagnosis. website. Accessed October 4th, 2023.
Definition / general
  • Deficiency in the production of glucocorticoids (e.g., cortisol) due to a disorder of the adrenal gland (primary adrenal insufficiency), inadequate pituitary adrenocorticotrophin hormone (ACTH; secondary adrenal insufficiency) or suppression of ACTH due to decreased corticotrophin releasing hormone (CRH; tertiary adrenal insufficiency)
Essential features
  • Clinical presentation of adrenal insufficiency is nonspecific; therefore, diagnosis is confirmed via laboratory testing
  • Low basal cortisol levels are indicative of insufficiency; abnormal response on the ACTH stimulation test is confirmatory
  • Concurrent high or low pituitary ACTH levels can differentiate between primary and secondary / tertiary adrenal insufficiency, respectively
  • Additional laboratory work up is needed to confirm the etiology of primary adrenal insufficiency; the most common causes are autoimmune adrenalitis in adults and congenital adrenal hyperplasia in children
Diagrams / tables

Contributed by Sarrah Lahorewala, B.D.S., Ph.D. and Roger L. Bertholf, Ph.D.
Adrenal insufficiency testing flowchart

Adrenal insufficiency testing flowchart

Primary adrenal insufficiency testing flowchart

Primary adrenal insufficiency testing flowchart

Adrenal steroid metabolism

Adrenal steroid metabolism

Clinical features
  • Clinical symptoms are often vague and nonspecific
  • Weight loss, anorexia, nausea and vomiting, postural dizziness, headaches, weakness, fatigue, hyponatremia, hypoglycemia, muscle cramps and abdominal pain
  • Primary adrenal insufficiency only: skin hyperpigmentation, salt craving, hyperkalemia, postural hypotension and volume depletion
  • Adrenal crisis: life threatening medical emergency mainly seen in primary adrenal insufficiency patients or in secondary / tertiary adrenal insufficiency under conditions of severe physiologic stress
    • Features: severe hypotension and shock, often accompanied by loss of consciousness
  • Reference: Lancet 2021;397:613
Laboratory diagnosis
  • Cortisol typically peaks in the morning
    • Early morning (8:00 AM) plasma or serum cortisol < 5 μg/dL (< 140 nmol/L) highly suggestive of adrenal insufficiency (J Clin Endocrinol Metab 2016;101:364)
    • Basal cortisol > 14 μg/dl (> 400 nmol/L) on commonly used automated immunoassays excludes adrenal insufficiency (Clin Endocrinol (Oxf) 2017;86:177)
    • ACTH levels in conjunction with low morning cortisol:
      • High ACTH > 2 fold the upper reference limit → primary adrenal insufficiency (absence of feedback loop to pituitary gland)
      • Low ACTH → secondary or tertiary adrenal insufficiency
    • Note: serum / plasma cortisol measures total cortisol (i.e., cortisol bound to cortisol binding globulin [CBG] and albumin)
    • Free cortisol can be measured in saliva and urine
      • Salivary free cortisol can be utilized for screening
      • Recommended for the diagnosis of critical illness related corticosteroid insufficiency (CIRCI) in critically ill patients (Crit Care Med 2017;45:2078)
      • Urinary free cortisol commonly used for the diagnosis of Cushing syndrome (hypercorticolism); not recommended for adrenal insufficiency testing
  • ACTH stimulation test (cosyntropin stimulation test)
    • Diagnostic gold standard test for primary adrenal insufficiency
      • Cosyntropin: synthetic form of the biologically active region of ACTH
      • Standard dose: 250 μg for adults and children ≥ 2 years of age, 125 μg for children < 2 years of age and 15 μg/kg for infants
      • Cortisol levels measured at baseline and 30 and 60 minutes after cosyntropin administration
    • Peak cortisol levels < 18 μg/dL (500 nmol/L) at 30 or 60 minutes confirms adrenal insufficiency diagnosis (J Clin Endocrinol Metab 2016;101:364)
    • Low dose cosyntropin stimulation test (1 μg) not recommended
    • Note:
      • Test cannot differentiate between primary and secondary adrenal insufficiency
      • Stimulated cortisol levels may appear normal in cases of acute onset secondary or tertiary adrenal insufficiency (e.g., post recent pituitary / brain surgery or trauma)
  • Multiday ACTH stimulation test
    • Can differentiate between primary and secondary (or tertiary) adrenal insufficiency
    • Rationale:
      • Chronic ACTH deficiency in secondary / tertiary adrenal insufficiency leads to adrenocortical atrophy and decreased responsiveness to stimulation
      • This results in an absent or low cortisol response 30 - 60 minutes after cosyntropin / Synacthen administration
      • Can be overcome by sustained ACTH stimulation, from 8 hours to 5 days
    • Dosage: single intramuscular or intravenous dose, 250 μg/day
  • Insulin tolerance test (ITT)
    • Can differentiate primary from secondary adrenal insufficiency
    • Can also identify acute onset central adrenal insufficiency not detected by the ACTH stimulation test
    • Rationale: hypoglycemia is a potent stressor for activation of the hypothalamus pituitary adrenocortical axis
    • IV insulin (0.1 U/kg body weight) administered after overnight fasting, with samples collected at baseline and variable intervals for up to 120 minutes
      • Hypoglycemia confirmed by > 50% reduction in glucose concentration below baseline or at concentration < 45 mg/dL
    • Low cortisol (post ITT induced hypoglycemia) confirms adrenal insufficiency
      • Concurrent high ACTH → primary adrenal insufficiency; low ACTH → secondary or tertiary adrenal insufficiency
    • Note: high risk test due to the sequelae of severe hypoglycemia
  • Metyrapone test
    • Metyrapone: blocks the conversion of 11-deoxycortisol to cortisol, causing decreased cortisol while increasing ACTH and 11-deoxycortisol
    • No increase in ACTH and 11-deoxycortisol confirms adrenal insufficiency
    • Dosage: 30 mg/kg body weight
    • Administered at midnight and levels of cortisol, ACTH and 11-deoxycortisol measured next morning at 8:00 AM
    • Note: can precipitate an adrenal crisis due to aggravated hypocortisolemia
  • CRH stimulation test
    • Can differentiate between secondary and tertiary adrenal insufficiency
    • Not recommended in routine practice
Additional testing for primary adrenal insufficiency
  • Mineralocorticoid (body salt balance) function evaluation
    • Tests for serum electrolytes, aldosterone levels and plasma renin concentration / activity
    • Hyponatremia, hyperkalemia, decreased aldosterone and increased renin concentration (or activity) indicates primary adrenal insufficiency diagnosis
    • Autoantibodies against 21-hydroxylase
      • Autoimmune primary adrenal insufficiency: most common cause of primary adrenal insufficiency in the western world
    • Congenital adrenal hyperplasia (CAH) testing
      • CAH: autosomal recessive disorder of defective steroidogenesis
      • Most cases are due to 21-hydroxylase deficiency (95%), with 11-hydroxylase deficiency accounting for the majority of the remaining cases
      • Screening: elevated 17-hydroxyprogesterone
      • Second tier screening: 17-hydroxyprogesterone measured by liquid chromatography-mass spectrometry (LC-MS); if not available, cosyntropin stimulation test should be performed (J Clin Endocrinol Metab 2018;103:4043)
      • Basal or cosyntropin stimulated 17-hydroxyprogesterone > 1,000 ng/dL is diagnostic
        • Usually > 5,000 ng/dL in classic CAH
      • 21-deoxycortisol:
        • Due to 21-hydroxylase deficiency (in CAH), accumulated 17-hydroxyprogesterone is converted to 21-deoxycortisol by 11-hydroxylase
        • Can be used for CAH screening
        • More specific than 17-hydroxyprogesterone as a marker for 21-hydroxylase deficiency CAH (J Pediatr 2021 Mar;230:161)
        • Virtually absent in normal patients and in CAH cases caused by 11-hydroxylase deficiency
      • Confirmatory test: genotyping
Factors that can impact test results
  • Levels of CBG: total cortisol can appear to be falsely elevated or decreased due to a corresponding change in CBG levels (J Pediatr Endocrinol Metab 2018;31:107)
  • Albumin: cortisol binds to albumin and therefore measured total cortisol can be affected by albumin concentration, albeit to a lesser extent than CBG
  • Pregnancy: cortisol and CBG increase in pregnancy and may cause normal appearing morning cortisol levels; higher diagnostic thresholds for the cosyntropin stimulation test are indicated (Curr Opin Endocrinol Diabetes Obes 2017;24:184)
Board review style question #1
A patient presents to the clinic with low basal cortisol, high ACTH, hypokalemia, hyperpigmentation and anti 21-hydroxylase antibodies. What is the patient's likely diagnosis?

  1. Adrenoleukodystrophy
  2. Autoimmune primary adrenal insufficiency
  3. Congenital adrenal hyperplasia
  4. Secondary adrenal insufficiency
Board review style answer #1
B. Autoimmune primary adrenal insufficiency. Low basal cortisol, high ACTH, hypokalemia and hyperpigmentation are all features of primary adrenal insufficiency. Autoantibodies against 21-hydroxylase are detected in 90% of patients with autoimmune adrenalitis.

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