Low Sodium Serum and Orthostatic Hypotension: Need Advice

White FM, 37, lacto-ovo-pesco vegetarian for 13 years, healthy weight, very active (hot yoga, weight training, outdoor gardening, etc.). I do have GERD and have been taking Pepcid for 9 years, allegies and have been taking Claritin/Clarinex, and on bc pill.

I went to see a nutritionist yesterday

[Kevin Pho, MD]

The easiest answer would be volume depletion.  This can cause orthostatic hypotension, a low serum osmolality as well as the low sodium.  Rechecking the lab tests after fluid repletion would be the first thing to do.

A sodium of 133 is only borderline low - considering normal is 135. However, checking for things like SIADH (syndrome of inappropriate secretion of ADH) can be considered and treated for (a discussion of water restriction would be the appropriate treatment).

A low anion gap can be caused by hyperkalemia, hypercalcemia, hypermagnesemia, or severe lithium intoxication.  Multiple myeloma can also lead to a low anion gap - this should be evaluated by your physician (a serum protein electrophoresis would be the inital test for this).

I would discuss these options with your primary care physician.  A referral to a kidney specialist can be considered if the sodium continues to be low.

Followup with your personal physician is essential.

This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.

Kevin, M.D.
http://www.straightfromthedoc.com