Serum sodium disorders are generally a marker of water balance in the body. Thus, hypernatremia is most often caused by an overall deficit of total body water. Other unique circumstances may lead to excess salt, without an impact on the body\'s total water volume. Hypernatremia is commonly acquired in both the hospital and community. As hypernatremia is associated with increased morbidity and mortality, treatment should be initiated promptly. In this review, we will discuss the pathophysiology and management of the main types of hypernatremia, which can be categorized as either a loss of water or gain of sodium that can be mediated by renal or extrarenal mechanisms.

BACKGROUND: Polyporus umbellatus (Pers.) Fries (Polyporaceae, Zhuling ) has been commonly used in medicine for a wide range of ailments related to the edema, scanty urine, vaginal discharge, urinary dysfunction, as well as jaundice and diarrhea.
OBJECTIVE: The present paper reviewed the traditional uses, propagation, phytochemistry, pharmacology, pharmacokinetics and quality control of Polyporus umbellatus.
METHODS: All the available information on Polyporus umbellatus was collected via a library and electronic search (using Web of Science, Pubmed, ScienceDirect, Splinker, Google Scholar, etc.).
RESULTS: Phytochemical studies showed the presence of many valuable secondary metabolites such as steroids, polysaccharides, anthraquinones and nucleosides. Crude extracts and isolated compounds showed a wide spectrum of pharmacological activities including diuretic, nephroprotective, anti-cancer, immuno-enhancing, hepatoprotective, anti-inflammatory and antioxidative activities. The pharmacokinetic studies demonstrated that the ergosterol and ergone had a high distribution and absorption in the plasma and the two main components of Polyporus umbellatus were mainly excreted by faeces. The determination of multiple chemical components was successfully applied to the quality control of Polyporus umbellatus.
CONCLUSIONS: Modern phytochemical, pharmacological and metabonomic investigations showed that the crude extracts and isolated compounds from Polyporus umbellatus possess many kinds of biological functions, especially in the diuretic activities and the treatment of kidney diseases as well as anti-cancer, immuno-enhancing and hepatoprotective activities. The pathways of the distribution, absorption, metabolism and excretion of main steroidal compounds were clarified by pharmacokinetic studies. Most of the pharmacological studies were conducted using crude and poorly characterized extracts of Polyporus umbellatus in animals especially in case of diuretic activities and the treatment of kidney diseases. Thus, more bioactive components especially diuretic compounds should be identified using bioactivity-guided isolation strategies and the possible mechanism of action as well as potential synergistic or antagonistic effects of multi-component mixtures derived from Polyporus umbellatus need to be evaluated integrating pharmacological, pharmacokinetic, bioavailability-centered and physiological approaches. In addition, more experiments including in vitro, in vivo and clinical studies should be encouraged to identify any side effects or toxicity. These achievements will further expand the existing therapeutic potential of Polyporus umbellatus and provide a beneficial support to its future further clinical use in modern medicine.