Unmeasured Osmoles: The Hidden Solutes Obscuring a Hyponatremia Evaluation.

Hyponatremia is defined as serum sodium less than 135 mEq/L and is principally a result of water excess relative to total body sodium content. The evaluation of hyponatremia is incomplete without a careful assessment of the patient's volume status, history, and acquisition of both serum and urine osmolality and sodium studies. Many of these studies can be affected by various clinical factors, and these nuances should be considered while interpreting the results.

A 90-year-old man with hyperphosphatemia.

Hyperphosphatemia is a common condition in patients with decreased kidney function, and without treatment, it can lead to a variety of clinical consequences. However, the presence of hyperphosphatemia in patients with normal kidney function may be true or spurious. We present a case of pseudohyperphosphatemia in a patient with monoclonal gammopathy.

Chronic kidney disease associated with environmental toxins and exposures.

People are exposed to various potentially toxic agents and conditions in their natural and occupational environments. These agents may be physical or chemical, may enter the human body through oral, inhalational, or transdermal routes, and may exert effects on all organ systems. Several well-known as well as lesser known associations exist between chronic kidney disease (CKD) and both environmental agents and conditions, such as heavy metals, industrial chemicals, elevated ambient temperatures, and infections.