Insulinoma differential diagnosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Amandeep Singh M.D.[2]

Overview

Insulinoma must be differentiated from other diseases that cause features of hypoglycemia like altered mental status/confusion, profuse sweating and visual disturbances (blurring/diplopia). These are classified on the basis of laboratory findings into exogenous insulin, oral hypoglycemic agents (e.g. Sulphonylureas), Nesidioblastosis, insulin autoimmune hypoglycemia.

Differentiating insulinoma from other Diseases

Insulinoma must be differentiated from other diseases that cause features of hypoglycemia. These are classified on the basis of laboratory findings.

Differentials for Hypoglycemia on the basis of Laboratory findings:[1]

Diagnoses Laboratory Findings differentiating among causes of Hypoglycemia
S.Glucose
(mg/dL)
C Peptide (pmol/L) S.Insulin (μU/mL) S.Proinsulin
(pmol/L)
S. Beta hydroxybutyrate Glucose increase after glucagon(mg/dL) Oral Hypoglycemic agent Antibodies to Insulin
Normal/Fasting <55 <200 <3 <5 >2.7 <25 - -
Exogenous Insulin <55 <200 >>3 <5 ≤2.7 >25 - -
Insulinoma <55 ≥200 ≥3 ≥5 ≤2.7 >25 - -
Nesidioblastosis
Post gastric bypass hypoglycemia (PGPH)
Insulin autoimmune hypoglycemia <55 >>200 >>3 >>5 ≤2.7 >25 - +
Oral hypoglycemic agent <55 ≥200 ≥3 ≥5 ≤2.7 >25 + -
IGF¤ <55 <200 <3 <5 ≤2.7 >25 - -

‡ Free C-peptide and proinsulin concentrations are low
¤ IGF= Insulin Growth Factor, Increased pro-IGF-2, free IGF-2, IGF-2/IGF-1 ratio

Differentiating hypoglycemia from other diseases that cause autonomic hyperactivity symptoms :

Disease Clinical Manifestation Investigations
Symptoms Signs
Palpitations Fever Sweating Headache
Hypoglycemia + - + +
Anxiety disorders + - + +
  • Patient looks irritable
  • Rapid pulse and may be irregular
  • Normal investigations
Pheochromocytoma + + + +
Arrhythmia + - - -
  • Irregular pulse
  • ECG changes according to the cause
Hyperthyroidism + + + +

References

  1. Cryer PE, Axelrod L, Grossman AB, Heller SR, Montori VM, Seaquist ER; et al. (2009). "Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline". J Clin Endocrinol Metab. 94 (3): 709–28. doi:10.1210/jc.2008-1410. PMID 19088155.
  2. Lenders JW, Pacak K, Walther MM, Linehan WM, Mannelli M, Friberg P; et al. (2002). "Biochemical diagnosis of pheochromocytoma: which test is best?". JAMA. 287 (11): 1427–34. PMID 11903030.
  3. Bravo EL (1991). "Pheochromocytoma: new concepts and future trends". Kidney Int. 40 (3): 544–56. PMID 1787652.

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