Wrist: Madelungs deformity – deformity wherein the wrist bones are not formed properly due to a genetic disorder. Terminology
Valgus is a term for outward angulation of the distal segment of a bone or joint. The opposite condition is called varus, which is a medial deviation of the distal bone. The terms varus and valgus always refer to the direction that the distal segment of the joint points. The original Latin definitions for varus and valgus were the opposite of their current usage. For a discussion of the etymology of these words, see the entry under varus. A mnemonic to remember the two deformities is that valgus contains an "L", for Lateral deviation. See also
Varus deformity

References

Canale & Beaty: Campbells Operative Orthopaedics, 11th ed. - 2007 - Mosby, An Imprint of Elsevier
Bowed Leg (Varus) and Knock-Knee (Valgus) Malalignment: Everything You Need to Know to Make the Right Treatment Decision-Understanding lower limb malalignment-Tibial osteotomy for bowed legs, Noyes, Frank R. and Barber-Westin, Sue, Amazon Digital Version, Publish Green (October 6, 2013)


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Hyponatremia with elevated tonicity can occur with high blood sugar, causing an shift of excess free water into the serum. Pathophysiology
The causes of and treatments for hyponatremia can only be understood by having a grasp of the size of the body fluid compartments and subcompartments and their regulation; how under normal circumstances the body is able to maintain the sodium concentration within a narrow range (homeostasis of body fluid osmolality); conditions can cause that feedback system to malfunction (pathophysiology); and the consequences of the malfunction of that system on the size and solute concentration of the fluid compartments. Normal homeostasis
There is a hypothalamic-kidney feedback system which normally maintains the concentration of the serum sodium within a narrow range. This system operates as follows: in some of the cells of the hypothalamus, there are osmoreceptors which respond to an elevated serum sodium in body fluids by signalling the posterior pituitary gland to secrete antidiuretic hormone (ADH) (vasopressin). ADH then enters the bloodstream 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 kidney tubule. Also, no thirst is experienced. These two act in concert to raise the serum sodium to the normal range.