17 days at the VA – day 13


Category : Medical Rants

Several issues presented from the patient discussed over the past 2 days.  The patient is greatly improved.  His laboratory tests have improved greatly, as has his mental status and ability to ambulate.


Electrolyte panel
Na 132 Cl 85 BUN 73
K 2.8 HCO3 37 creat 2.8
Blood Sugar 205

then 2 days later


Electrolyte panel
Na 141 Cl 106 BUN 26
K 3.7 HCO3 28 creat 1.3
Blood Sugar 194

Two more teaching points about this patient.  One reader asked:

I was expecting hypernatremia with volume contraction.  How volume contraction leads to hyponatremia?

This question reflects a common mistake.  Disorders of serum sodium reflect problems of water handling.  Patients with volume contraction can be dehydrated (increased serum sodium), normal hydration or overhydrated (decreased serum sodium).  The key here is that volume contraction implies salt losses.  If the patient did not have access to fluids he might have become hypernatremic.  However, our patient's thirst is intact so he drank water.  Volume contraction stimulates ADH release, so he holds on to the water (makes concentrated urine, retaining free water).  The excess free water leads to decreased serum sodium.

On admission the resident order lab tests to calculate both the fractional excretion of sodium and of urea. His urine Na 52, urea 460, creatinine 73.  We traditionally use FeNa to support volume contraction.  His FeNa was 1.5%, which is not helpful.  The resident correctly understood that the patient had taken a diuretic, which makes the FeNa less helpful.  In those situations we use the FeUrea.  His calculates as 24.2%.  We know that values less than 35% support volume contraction.

While we may not have needed the calculation in this patient, the lab tests are relatively inexpensive and they do provide additional support for our clinical hypothesis.

We recently sent a patient to the unit looking septic.  Currently, the unit team suspect Macrophage Activation Syndrome.  I do not really understand this syndrome well, so I plan to read about it today.  I will try to explain it tomorrow.  My simple understanding is that we have a patient who has features consistent with sepsis, but negative cultures.  Thus, this syndrome describes a set of  "mystery" patients.  Much more to learn today.

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