Thanks Joel for presenting a great case! And thanks to James Lundblad for coming and sharing his wisdom. This was a case of a patient who presented with hypoglycemia found to have a new diagnosis of widespread diffuse large B-cell lymphoma.
1) In approaching hypoglycemia, document Whipple’s triad of (1) symptoms of hypoglycemia (2) low glucose at time of symptoms (3) resolution of symptoms after correction of hypoglycemia
2) Symptoms of hypoglycemia can be classified as (1) secondary to adrenergic stimulation (tremors, anxiety, sweating) and (2) neuroglycopenia (confusion, fatigue, loss of consciousness, blurry vision, seizures, coma, etc.)
3) Tumor-induced hypoglycemia can be secondary to several etiologies including high glucose consumption from rapidly dividing tumors OR paraneoplastic production of insulin or related hormones (IGF-1, somatostatin, etc)
Want to learn more?
Framework for hypoglycemia
Hypoglycemia can be broken down into those caused by increased insulin and those caused by decreased glucose.
- 1) Exogenous – think accidental vs surreptitious ingestion of insulin or sulfonylureas
- 2) Endogenous – think insulinoma (more likely to have neuroglycopenic symptoms), anti-insulin antibodies, islet cell hypertrophy
Decreased circulating glucose
- 1) Malabsorption – usually in patient s/p gastric bypass (usually see postprandial hypoglycemia)
- 2) High glucose consumption – rapidly dividing tumors
- 3) Poor gluconeogenesis/ low glycogen stores – malnutrition (eg alcohol use d/o), critical illness (sepsis, liver failure, renal failure, heart failure, adrenal insufficiency), ingestion of ackee fruit (per Peter Sullivan)
- 4) Low glucagon - pancreatic failure of any cause
Tests to distinguish these causes (c-peptide, insulin, proinsulin, serum ketones) should be measured at the time of documented hypoglycemia or in consultation with endocrinology during a 72-hour fast.
This is a great review article and table (below) of causes of lactic acidosis. While we usually think of and need to rule out decreased oxygen delivery/ tissue perfusion, there is a list of other conditions to think about such as diabetes, cancer 2/2 warburg effect, decreased clearance from liver disease, metformin, medications/ ingestions, and thiamine deficiency.