720 North Tustin Avenue Suite 104 Santa Ana, CA 92705-3606 Phone: (714) 565-1032 Fax: (714) 565-1035
Jeremy E. Kaslow, MD, FACP, FACAAI Physician and Surgeon Board Certified Internal Medicine
NOTICE TO CONSUMERS Medical Doctors are licensed and regulated by the Medical Board of California (800) 633-2322 www.mbc.ca.gov
maintains the proper acid-base equilibrium for the proper osmotic balance.
Normally it is the most abundant cation (positively charged electrolyte) in the
fluid outside of the cell (extra-cellular fluid or ECF). Like all cations,
sodium has alkaline properties. Sodium is of greatest importance in osmotic
regulation of extra-cellular fluid balance and acid balance, as well as renal,
cardiac and adrenal functions. It is needed to maintain the sodium-potassium
pump, which transports sodium out of the cell and potassium into the cell. This
electrical pump creates a small amount of voltage across the cell membrane and
is what nerve conduction depends upon. Given this fact, it is easy to
understand why potassium is concentrated in the cells and sodium in the
with potassium, acid-base influences, and general vascular volume is implied as
well. To roughly assess electrolyte balance, add Cl and CO2 and
subtract them from the sodium level. The result of 12-16 indicates good
electrolyte balance. The value of sodium is based on its relationship to
potassium, chloride, pH, anion gap, osmolality, etc. The urinalysis and
specific gravity can give further clues as to the root cause. Combining this
information gives an excellent indicator of adrenal cortical function.
The sodium level by itself is
often not useful unless it is severely out of the normal range. It can only be
interpreted in relation to the serum potassium and chloride levels.
Optimum Values: 142-145 mmol/L
Sodium levels may be elevated
Water deficit (diabetes insipidus, loss of glucose in
the urine due to diabetes mellitus, excessive sweating, inadequate water
Water deficit exceeding sodium deficit (diarrhea,
diabetes mellitus, renal disease)
Excessive intake of sodium (sodium bicarbonate or
salt tablet use, sea water, drinking water from water softeners on a
prolonged and regular basis.)
Adrenal Cortex Hyper-function. Aldosterone
is produced by the adrenal cortex, with excessive production the body
retains sodium from the kidney in exchange for urinating out potassium. This
is why you may get relatively low potassium if your adrenal cortex is
producing too much aldosterone.
Congestive Heart Failure. Because the heart is not
pumping the blood to the kidneys with enough power, the kidney starts to
reclaim as much sodium as possible. Unfortunately this doesn't help the
heart because the extra fluid that stays with sodium stresses the heart
Insufficient Anti-Diuretic Hormone production by the
hypothalamic-pituitary complex. As a result, the body loses water but
retains the sodium.
Alcohol intake reduces the sodium lost in the urine.
Insufficient parathyroid hormone results in reduced
loss of sodium in the urine with resultant increased retention of serum
Sodium may be reduced
Hyperglycemia and Diabetes mellitus lower serum
sodium because the sodium is carried out in the urine with the extra
Excess Perspiration leads to loss in the sweat.
Adrenal Cortex Hypo-function. Aldosterone is produced
by the adrenal cortex; with insufficient production the body loses sodium
in the urine in exchange for potassium. This is why you may get relatively
low sodium with relatively elevated serum potassium with insufficient
production of aldosterone.
Excess progesterone blocks the action of aldosterone
but insufficient progesterone results in greater loss of sodium in the
urine. Both conditions can lead to lowered sodium levels.
Diarrhea and metabolic alkalosis.
Syndrome of Inappropriate Anti-Diuretic Hormone
production by the hypothalamic-pituitary complex. This hormone causes
water retention and sodium excretion. As a result you don't get rid of
water and the extra water you hold onto dilutes out the sodium.
Water intoxication (including tap water enemas, beer)
Third spacing (burns, ascites, effusions)
Excess ADH (SIADH, pain, medications)
depend on the rate that the sodium drops and are primarily neurologic. Check
for renal function with a urine sodium done at same time as serum sodium and
osmolality. Insufficient adrenal function is not an uncommon finding with a
relatively lower sodium and higher potassium.