Articles on Medical Diseases and Conditions

Entries for the ‘Serum Electrolytes and Protein-Calorie Malnutrition’ Category

Tests in Calcium Disorders: Hypercalcemia

Symptoms referable to hypercalcemia itself are very nonspecific; they include vomiting, constipation, polydipsia and polyuria, and mental confusion. Coma may develop in severe cases. There may be renal stones or soft tissue calcification. Hypercalcemia is most often detected on routine multitest biochemical screening panels, either in asymptomatic persons or incidental to symptoms from some disease […]

Serum Electrolyte Panels

Many physicians order serum “electrolyte panels” or “profiles” that include sodium potassium, chloride, and bicarbonate (“CO2”; when “CO2” is included in a multitest electrolyte panel using serum, bicarbonate comprises most of what is being measured). In my experience, chloride and “CO2” are not cost effective as routine assays on electrolyte panels. If there is some […]

Serum Chloride

Chloride is the most abundant extracellular anion. In general, chloride is affected by the same conditions that affect sodium (the most abundant extracellular cation) and in roughly the same degree. Thus, in the great majority of cases, serum chloride values change in the same direction as serum sodium values (except in a few conditions such […]

Clinical Symptoms of Electrolyte Imbalance

Before I conclude the discussion of sodium and potassium, it might be useful to describe some of the clinical symptoms of electrolyte imbalance. Interestingly enough, they are very similar for low-sodium, low-potassium, and high-potassium states. They include muscle weakness, nausea, anorexia, and mental changes, which usually tend toward drowsiness and lethargy. The electrocardiogram (ECG) in […]


High potassium values are not uncommon in hospitalized patients, especially in the elderly. One study reported serum potassium levels more than 5 mEq/L in 15% of patients over age 70. However, hyperkalemia is found in relatively few diseases. Decreased renal potassium excretion. Renal failure is the most common cause of hyperkalemia, both in this category […]


Hypokalemia has been reported in about 5% of hospitalized patients. Abnormalities in potassium have many similarities to those of sodium. Some conditions with potassium abnormalities are also associated with sodium abnormalities and were discussed earlier. Several different mechanisms may be involved. Inadequate intake. Ordinarily, 90% of ingested potassium is absorbed, so that most diets are […]

Serum Potassium Abnormalities

The potassium level in serum is about 0.4-0.5 mEq/L higher than the potassium level in whole blood or plasma (literature range, 0.1-1.2 mEq/L). This is attributed at least in part to potassium released from platelets during clotting. Serum specimens may have artifactual potassium level increase additional to that of normal clotting in patients with very […]


Hypernatremia is much less common than hyponatremia. It is usually produced by a severe water deficit that is considerably greater than the sodium deficit and is most often accompanied by dehydration (see the box on this page). The water deficit can be due to severe water deprivation, severe hypotonic fluid loss (renal or nonrenal) without […]

Laboratory Investigation of Hyponatremia

When the serum sodium level is unexpectedly low, one must determine whether it is due to false (artifactual) hyponatremia, sodium depletion, hemodilution, the IADH syndrome, or the reset osmostat syndrome. The first step is to rule out artifactual causes. The serum sodium tests should be repeated and blood redrawn if necessary, avoiding areas receiving IV […]

Disorders Simulating Inappropriate Antidiuretic Hormone

Refractory dilutional syndrome is a moderately frequent condition in which many features of IADH are seen but the classic syndrome is not present. The dilutional hyponatremia of cirrhosis and congestive heart failure may sometimes be of this type, although usually other mechanisms can better account for hyponatremia, such as overuse of diuretics. However, in some […]