Electrolytes & Hydration | Importance of Electrolytes | nuun
Nov 20, We need a balance of several types of electrolytes to function. Electrolyte levels can change in relation to water levels in the body as well as. Treatment is restoring lost water and mineral salts (such as sodium and potassium) that are dissolved in the blood (electrolytes), usually by drinking but. Absorption of Water and Electrolytes. The small intestine must absorb massive quantities of water. A normal person or animal of similar size takes in roughly 1 to .
Exertion under any of these conditions can cause up to a fold increase in water loss from skin and lungs. Diarrhea can increase intestinal loss dramatically. M is minimal urine volume at maximal solute concentration. Ox is water of oxidation. Because the kidney must excrete waste products, the solute load—composed of the nitrogen-containing breakdown products of protein metabolism principally ureasulfates, phosphates, and other electrolytes—determines the minimal volume of water required for urine formation.
Despite the kidney's ability to compensate, its limitations require the effective use of the thirst sensation to maintain water balance. If the sensation of thirst is not met by water consumption, or if the thirst mechanism is inoperative because of intense, sustained exertion, especially at a high altitude Buskirk and Mendez,dehydration will eventually result. Sources Although water, consumed as water, is a major source of liquid in some parts of the world, much of the water consumed in the United States is taken in the form of other beverages.
Median daily intake of water as such among respondents in the — Nationwide Food Consumption Survey was 2. Indaily per capita milk consumption was approximately one and one-third cups, per capita coffee and tea consumption was about one and one-half cups, and soft drink consumption was one and three-fourths cups per capita. Estimate of Requirements The primary determinant of maintenance water requirement appears to be metabolic Holliday and Segar,but the actual estimation of water requirement is highly variable and quite complex.
Because the water requirement is the amount necessary to balance the insensible losses which can vary markedly and maintain a tolerable solute load for the kidneys which may vary with dietary composition and other factorsit is impossible to set a general water requirement. However, there is so seldom a risk of water intoxication that the specified requirement for water is often increased to 1. Special attention must be given to the water needs of the elderly whose thirst sensation may be blunted.
Even though these people may be less physically active, they may still have a high water requirement, especially during the summer. If uncorrected, water depletion with heat exhaustion, resulting from inadequate replacement of fluid losses, can eventually cause a loss of consciousness and heat stroke NRC, b.
Pregnancy and Lactation Pregnancy is associated with an increased need for water because of the expanded extracellular fluid space, the needs of the fetus, and the amniotic fluid. A lactating woman, on the other hand, requires an increased volume of water to match that secreted in the milk.
Infants and Children Infants must be treated as a separate category for several reasons: It is prudent, therefore, to recommend an average water intake of 1. This figure corresponds to the water-to-energy ratio in human milk and common formulas and has been well established as a satisfactory level for the growing infant.
Excessive Intakes and Toxicity Toxicity results from the ingestion of water at a rate beyond the capacity of the kidneys to excrete the extra load, resulting in hyposmolarity. Such a condition is rarely observed in a normal healthy adult. The manifestations usually include a gradual mental dulling, confusion, coma, convulsion, and even death. Both the body content of sodium and its concentration in body fluids are under homeostatic control, and the volume of extracellular fluid is thus normally determined by its sodium content.
In addition to its role in regulating extracellular fluid volume, sodium is important in the regulation of osmolarity, acid-base balance, and the membrane potential of cells.
- Fluid and Electrolyte Balance
Sodium is also involved in active transport across cell membranes and must be pumped out in exchange for potassium in order to maintain an appropriate intracellular milieu—a process that requires an appreciable fraction of the energy required in the basal metabolic state. Sodium homeostasis is maintained over a wide range of environmental and dietary circumstances, primarily through the action of the hormone aldosterone on the renal tubules of the kidney.
When sodium intake is high, the aldosterone level decreases and urinary sodium increases. When dietary sodium intake is low, the aldosterone level increases and urinary excretion of sodium rapidly falls almost to zero. Although the kidney can thus conserve sodium, there is some obligatory loss via feces and sweat. Sodium deficiency resulting from low dietary intake thus does not normally occur, even among those existing on very low sodium diets Page, Even relatively heavy sweating does not normally create a need to provide salt supplements Conn, The body may be depleted of sodium under extreme conditions of heavy and persistent sweating, or where trauma, chronic diarrhea, or renal disease produce an inability to retain sodium Gothberg et al.
These latter conditions require medical attention. Sources other than table salt—e. By using a lithium chloride marker to trace the use of salt in cooking and at the table, Sanchez-Castillo et al. Because of the high proportion of dietary sodium accounted for by processing, the highest salt intakes are normally associated with a diet high in processed foods and the lowest intakes are associated with diets emphasizing fresh fruits, vegetables, and legumes.
Usual levels of sodium consumption have been estimated in dietary surveys by assessing salt intake and by measuring urinary sodium. Reported dietary intakes of sodium range from 1. The discretionary intake of sodium is quite variable and can be quite large. In one day study, males were found to add about 5. Because of the difficulty of assessing sodium use from dietary recall, dietary surveys probably underestimate total sodium intake, even when contributions of water and other marginal sources are included.
Dahl subsequently reported a mean sodium chloride intake of Estimate of Requirements Calculations of sodium requirements shown in Table are based on estimates of what is needed for growth and for replacement of obligatory losses.
The amount needed to support growth depends on the rate at which extracellular fluid volume is expanded, a rate that varies with age and reproductive status. Adults In a temperate climate, the healthy adult can maintain sodium balance with a very low intake of sodium Kempner, Obligatory dermal losses have been assumed to range from 46 to 92 mg 2 to 4 mEq per day Fregley, Such an intake is substantially exceeded by usual diets in the United States, even in the absence of added sodium chloride.
Although no optimal range of salt intake has been established, there is no known advantage in consuming large amounts of sodium, and clear disadvantages for those susceptible to hypertension. From this and other considerations, a Food and Nutrition Board committee recently recommended that daily intakes of sodium chloride be limited to 6 g 2. Pregnancy and Lactation During pregnancy, there is an increased need for sodium because of the increased extracellular fluid volume in the mother, the requirements of the fetus, and the level of sodium in the amniotic fluid.
This need is normally met in part by physiological responses of the renin-angiotensin-aldosterone systems Pike and Smiciklas, Since the average intake is, as has been noted, considerably above that, the sodium requirement for pregnancy is met by usual salt intake.
Lactation increases sodium requirements considerably. Since human milk contains about 7. This increase is easily met by the usual dietary sodium intake. Infants and Children The sodium requirement is obviously highest in infants and young children in whom extracellular fluid volume is rapidly expanding.
Forbes calculated that from birth to 3 months of age, 0. At 6 months of age, the daily requirement for growth is approximately 0. According to calculations by Cooke et al. Except for the premature infant, in whom hyponatremia can occur Roy et al. The American Academy of Pediatrics has estimated that there is a threefold increase in dietary sodium between 2 and 12 months of age AAP, Excessive Intakes and Toxicity Acute excessive intake of sodium chloride leads to an increase in the extracellular space as water is pulled from cells to maintain sodium concentration.
The end result is edema and hypertension. Such acute toxicity from dietary sodium is not a concern, however, since as long as water needs can be met, the kidney can excrete the excess sodium. Sustained overconsumption of sodium, particularly as salt, has been related to development of hypertension in sensitive individuals NRC, ; Tobian, This small percentage of extracellular potassium is, however, of great physiological importance, contributing to the transmission of nerve impulses, to the control of skeletal muscle contractility, and to the maintenance of normal blood pressure.
Potassium is lost from the body in the urine and, to a lesser extent, in gastrointestinal secretions, whereas only minimal amounts are excreted in sweat.
Everything you need to know about electrolytes
Under normal circumstances, dietary deficiency of potassium does not occur. The most important cause of potassium deficiency is excessive losses, usually through the alimentary tract or the kidneys. Large alimentary potassium losses may occur through prolonged vomiting, chronic diarrhea, or laxative abuse.
The most common cause of excessive renal loss is the use of diuretic agents, especially for the treatment of hypertension.
Some forms of chronic renal disease and metabolic disturbances e. Deficiency symptoms include weakness, anorexia, nausea, listlessness, apprehension, drowsiness, and irrational behavior.
Severe hypokalemia may result in cardiac dysrhythmias that can be fatal. Dietary Sources and Usual Intakes Potassium is widely distributed in foods, since it is an essential constituent of all living cells.
Animal tissue concentration of potassium is fairly constant, but varies inversely with the amount of fat. Some potassium is also added in food processing, but the overall effect of processing on the food supply has been to increase the sodium and decrease the potassium NRC, Thus, the richest dietary sources are unprocessed foods, especially fruits, many vegetables, and fresh meats. The contribution of drinking water to potassium intake is negligible.
The mean concentration in household tap water was reported to be 2. Potassium intakes vary considerably, depending on food selection. Human milk contains about mg Infant formulas contain slightly more potassium than human milk on the average, and cow's milk contains almost 3 times as much, 1, mg 35 mEq per liter.
Estimate of Requirements Adults Potassium requirements have been evaluated in only a few studies. Fecal losses are less than mg 10 mEq per day, and renal losses may approach to mg 5 to 10 mEq per day Squires and Huth, Therefore, it would appear that the minimum requirement is approximately 1, to 2, mg 40 to 50 mEq per day. This test can also monitor the progress of treatment relating to a known imbalance.
Electrolytes: Uses, imbalance, and supplementation
A doctor will sometimes include an electrolyte panel as part of a routine physical exam. It can be performed on its own or as part of a range of tests. People are often given an electrolyte panel during a hospital stay. It is also carried out for those who are brought to the emergency room, as both acute and chronic illnesses can impact levels.
If the level of a single electrolyte is found to be either too high or too low, the doctor will keep testing this imbalance until levels are back to normal. If an acid-base imbalance is found, the doctor may carry out blood gas tests.
These measure the acidity, oxygen, and carbon dioxide levels in a sample of blood from an artery.
They also determine the severity of the imbalance and how the person is responding to treatment. Levels may also be tested if a doctor prescribes certain drugs known to affect electrolyte concentration, such as diuretics or ACE inhibitors.
Treatment One solution to a mild electrolyte imbalance involves simply drinking more water.
Treating an electrolyte imbalance involves either restoring levels if they are too low or reducing concentrations that are too high. If levels are too high, the treatment will depend on the cause of the excess.
Low levels are normally treated by supplementing the needed electrolyte.