Had the privilege of presenting another case to @rabihmgeha and @DxRxEdu on Friday-VMR and it was just mesmerizing hearing them talk through it step by step.
Here are some reflections on the fascinating topic discussed:
CAVE: spoiler alert ‼️
Here are some reflections on the fascinating topic discussed:
CAVE: spoiler alert ‼️
A 60ish M p/w a week of jaundice after Tx w/ bactrim 2 weeks ago. His PMH was significant for T2DM, HLD and he was on a statin and insulin Tx.
PE was notable for marked jaundice w/o signs of cirrhosis and no encephalopathy.
PE was notable for marked jaundice w/o signs of cirrhosis and no encephalopathy.
Labs: CBC wnl, liver tests w/ predominant cholestatic, but also hepatocellular pattern of injury
Na+ 113, SOsm 290, glucose 260, normal kidney function
At that time we found ourselves in the space of
hyponatremia w/ a normal serum osmolarity.
A short 🧵:
Na+ 113, SOsm 290, glucose 260, normal kidney function
At that time we found ourselves in the space of
hyponatremia w/ a normal serum osmolarity.
A short 🧵:
Approaching this rather uncommon clinical scenario we can think of 2 mechanisms, either
1. combination of a hyper- and hypoosmolar state (e.g. a patient w/ HHS and consecutive fluid depletion)
2. an artifact caused by the measurement of Na+ in the plasma
1. combination of a hyper- and hypoosmolar state (e.g. a patient w/ HHS and consecutive fluid depletion)
2. an artifact caused by the measurement of Na+ in the plasma
3 causes of laboratory artifact:
1. elevated TG (e.g. seen in acute pancreatitis or DKA): usually lipemic serum, that can alert the laboratory personnel
2. plasma cell dyscrasias w/ secretion of monoclonal antibodies and severe hyperproteinemia (usually >10g)
1. elevated TG (e.g. seen in acute pancreatitis or DKA): usually lipemic serum, that can alert the laboratory personnel
2. plasma cell dyscrasias w/ secretion of monoclonal antibodies and severe hyperproteinemia (usually >10g)
Last but not least and found to be the culprit in this case:
3. accumulation of lipoprotein X (seen in obstructive jaundice and high elevations of cholesterol): does NOT cause lipemic serum and is therefore easier missed
But what is lipoprotein X?
3. accumulation of lipoprotein X (seen in obstructive jaundice and high elevations of cholesterol): does NOT cause lipemic serum and is therefore easier missed
But what is lipoprotein X?
Lp X is an insoluble compound that forms when there is reflux of cholesterol and PL into circulation and therefore ↑ solid fraction of plasma. It does not accumulate in other diseases resulting in very ↑ cholesterol (e.g. familial hypercholesterolemia) & ↓ LDL-atherogenicity
Mechanism of pseudohyponatremia @NEJM
Serum sample is diluted before actual measurement is obtained -> if more than the normal fraction of serum (7% of volume) consists of proteins or lipids, the degree of dilution is underestimated, resulting in artificially low Na+ levels
Serum sample is diluted before actual measurement is obtained -> if more than the normal fraction of serum (7% of volume) consists of proteins or lipids, the degree of dilution is underestimated, resulting in artificially low Na+ levels
What to do if high suspicion?
Use direct ion-selective electrodes & direct potentiometry to confirm pseudohyponatremia (a concept that I have yet to understand).
Lipid electrophoresis can detect abnormally ↑ Lp X.
Use direct ion-selective electrodes & direct potentiometry to confirm pseudohyponatremia (a concept that I have yet to understand).
Lipid electrophoresis can detect abnormally ↑ Lp X.
Important Tx-💎:
Do not fluid deprive these patients (if you think SIADH) because it can further increase their serum viscosity & lead to hyperviscosity syndrome.
Remember: this is an artifact & osmolarity & tonicity of serum remain normal! Na+ needs NO Tx.
Tx: lipid apheresis
Do not fluid deprive these patients (if you think SIADH) because it can further increase their serum viscosity & lead to hyperviscosity syndrome.
Remember: this is an artifact & osmolarity & tonicity of serum remain normal! Na+ needs NO Tx.
Tx: lipid apheresis
Thank you again for this amazing discussion @DxRxEdu and @rabihmgeha!
Always such a treat with you all on VMR!
If this sparked your interest, consider joining us on daily VMRs. The learning environment and atmosphere are just so unique: clinicalproblemsolving.com/learn-live/
Always such a treat with you all on VMR!
If this sparked your interest, consider joining us on daily VMRs. The learning environment and atmosphere are just so unique: clinicalproblemsolving.com/learn-live/
Case courtesy: mayoclinicproceedings.org/article/S0025-…
Here is a helpful CPS: nejm.org/doi/10.1056/NE…
Sources: @UpToDate, @NEJM
Here is a helpful CPS: nejm.org/doi/10.1056/NE…
Sources: @UpToDate, @NEJM
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