Hyponatremia and signals the kidney to bring back sufficient solute-free water from the fluid in the kidney tubules to dilute the serum sodium back to normal, and this turns off the osmoreceptors in the hypothalamus. Also, thirst is stimulated. Normally, when mild hyponatremia begins to occur, that is, the serum sodium begins to fall below 135 mEq/L, there is no secretion of ADH, and the kidney stops returning water to the body from the renal tubule. Also, no thirst is experienced. These two act in concert to raise the serum sodium to the normal range. Hyponatremia occurs 1) when the hypothalamic-renal
Serum free light-chain measurement Serum free light-chain measurement Immunoglobulin light chains that are circulating in serum in a free (unbound) state are called free light chains (FLCs). Measurement of the serum level of FLCs became practical as a clinical blood test in recent decades. These tests are used as an aid in the diagnosis and monitoring of multiple myeloma and related disorders. There are two types of immunoglobulin light chain produced in humans, designated by the Greek letters kappa (κ) and lambda (λ). Comparing the ratio of κ FLCs to λ FLCs in a person's serum against reference ranges indicates whether that person may