Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Hypoosmolality
Introduction
Overview
Overview
Hyposmolality or hypoosmolality is the condition especially of a bodily fluid of having abnormally low osmolality.
Physiology of Osmolality
Physiology of Osmolality
Plasma osmolality is a function of the ratio of body solute to body water. Plasma osmolality is regulated by changes in water balance. Water intake is derived primarily from three sources:
- Ingested water
- Water contained in food
- Water produced from oxidation of carbohydrates, proteins, and fats.
Water losses occur in the urine and stool, as well as evaporation from the skin and respiratory tract. Alterations in plasma osmolality of as little as 1% – 2% are sensed by osmoreceptors in the hypothalamus. These receptors initiate mechanisms that affect water intake (via thirst) and water excretion (via antidiuretic hormone ADH) to return plasma osmolality to normal.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]