Potassium requirements

The body s normal daily potassium requirement is 0.5 to 1 mEq/kg (0.5 to 1 mmol/kg) or 40 to 80 mEq (40 to 80 mmol) to maintain a serum potassium concentration of 3.5 to 5 mEq/L (3.5 to 5 mmol/L). Potassium is the most abundant cation in the ICF, balancing the sodium contained in the ECF and maintaining electroneutrality of bodily fluids. Because the majority of potassium is intracellular, serum potassium concentration is not a good measure of total body potassium however, clinical manifestations of potassium disorders correlate well with serum potassium. The acid-base balance of the body affects serum potassium concentrations. Hyperkalemia is routinely seen in... 

Hypokalemia is common in the patient with liver failure who has normal renal function. Poor nutritional intake and vomiting may initiate this disorder. Severe vomiting may lead to volume contraction metabolic alkalosis, with increased renal excretion of potassium. Secondary hyperaldosteronism, seen in the liver failure patient with intravascular depletion, also increases renal excretion of potassium. Loop diuretic therapy causes increased renal excretion of potassium, whereas diarrhea from lactulose therapy increases fecal excretion of potassium. All these conditions can lead to profound hypokalemia. Therefore, potassium requirements in the liver failure patient receiving specialized nutritional support often are increased substantially. 

The daily normal potassium requirement is not well known, but is met in women and men by daily intakes of 1300 and 1600 mg, respectively (Anke et al. 2003). 

The normal potassium requirement of both sexes and diet forms is met (Table 4.2). Typically, men consume 25-40% more potassium than women, while vegetarians take in much more potassium than people with mixed diets. (Anke et al. 

Nursing mothers typically take in 15% more potassium than non-nursing women (Anke et al. 2003). At present, the normal daily potassium requirement of adults is not known, but for adults the minimum value has been cited as -1.6-2.0 g (Anonymous RDA 1989) or 2000 mg (Anonymous 2000). This requiremenf is an estimation, and is tantamount to a recommendation. A comparison of potassium intake measured by the duplicate portion technique and as calculated by the basket method showed an overestimation of calculated potassium intake by 30%. Hence, methods of potassium intake calculation should not be used (Anke etal. 2003). For example, Pittelkow (1992) calculated a daily potassium intake of 3.0 g kg for women and 4.0 g kg by men in Germany, but on average this was an overestimation by 25% for both groups. 

In dogs, potassium deficiency was produced with a dietary level < 0.3 g kg 90% DM, with morphological changes occurring in the heart, skeletal muscle and kidneys (Tate etal. 1978). The normal potassium requirement is met by a dietary level of 2.2-4.0 g kg (Georgievskii et al. 1982). 

The normal daily potassium requirement may be <1200-1500 mg for women and < 1500-1800 mg for men, and the balance of people with this intake is equalized (Anke et al. 2003). The German Society of Nutrition recommends a daily potassium intake of 2 g by adults (Anonymous 2000). 

Rapid venous injection of potassium into the blood stream or intramminal infusion with some form of potassium is extremely toxic because of the rapid absorption. Pigs can tolerate up to 10-fold the potassium requirement, if plenty of drinking water is provided (Faries 1958). 

Brink MF (1961) Potassium requirement of the immature ovine. PhD Thesis, University of Missouri, Columbia, MO. 

Chavez E and Kratzer FH (1973) The potassium requirement of poults. Poultry Sci LII 1542-1544. 

Deetz LE and Ringrose RC (1976) Effect of heat stress on the potassium requirement of the hen. 

Dennis RJ and Hemken RW (1978) Potassium requirement of dairy cows in early and midlactation. 

Leach JRRM (1974) Studies on the Potassium Requirement of the Laying Hen. J Nutr 104 684-686. 

Mengel K (1978) A consideration of factors which affect the potassium requirements of various crops. Potassium Research - Reviews and Trends. Proceedings, 11th Congress of the International Potash Institute, Bern, Switzerland, pp. 225 — 237. 

Telle PP, Preston RL, Kintner LD and Peander WH (1964) Definition of the ovine potassium requirements. J Anim Sci 23 59-66. 

Weil AB, Tucker WB and Hemken RW (1988) Potassium requirement of dairy calves. J Dairy Sci 71 1868-1872. 

Fig. 264 shows Brauer s apparatus for distilling Cs and Rb. Ordinary chemical glassware may be used. (However, according to Hevesy and Ldgstrup, distillation of potassium requires Pyrex apparatus.) Tube B is slightly inclined. The ampoules are... 

Potassium salts are not as abundant as sodium salts in food for two reasons first, because potassium salts are less abundant in nature than sodium salts and, second, because potassium salts are bitter and therefore are not added to food for seasoning. Leguminous plants are one of the richest sources of dietary potassium. The total potassium intake in man is much lower than the sodium intake. However, potassium intake is always sufficient to maintain potassium requirements because of the kidney s capacity to reabsorb potassium lost in the glomerular filtrate. 

The model structure of the surface of the iron catalyst may be used to explain the influence of different elements on the catalyst properties. The atoms of aluminium are able to be present on iron surfaces because it requires for a high concentration oxygen atoms, while potassium requires less of oxygen atoms in order to be stabilized on iron surfaces. Hence, alumina increases catalyst surface area, while alkali results in the declines of surface area. The model states that 0.48 wt% K2O is enough to cover the iron surface with a monolayer of potassium. Industrial catalysts contain usually from 0.5 wt% to 1 wt% K2O. An excess is required to form some bulk compounds with alumina, silicon, or calcium found in the catalyst. Because at least 10% of the potassium is permanently bound in these compounds, 0.55 wt% is considered to be a sufficient concentration. This conclusion is supported by the experimental results of Kowalczyk. It is found that the potassium concentration in doubly promoted catalysts leads to the highest activity in the range of 0.5-0.7 wt%. 

The net energy change associated with the formation of K and I ions is endothermic that is. energy must be supplied in order for the overall transfer of an electron from K to I to take place. The ionization of potassium requires the input of 419 kJ/mol, and the electron affinity of iodine is only 295 kJ/mol [ S ection 7.4]. If a mole of KI were to form as we have described it. an input... 

Nitrogen requirements are the same as those for oats and lye. 120 kg/ha of N are recommended for a mineral soil at SNS 1. Remember nutrient contributions from organic manures. Nitrogen should be top-dressed at the end of Maich/early April depending on the SNS indices. For phosphorus and potassium requirements see Table 13.3. 

RECOMMENDED DAILY ALLOWANCE OF POTASSIUM. The exact potassium requirements are unknown. But it is known that the daily intake on typical diets far exceeds the requirements. 

Sample processing is performed to get the sample into a form that can be analyzed. For a few kinds of analysis, the sample is analyzed without further processing or after minimal steps, such as grinding and mixing. Often, sample processing requires putting the sample into solution. Sample dissolution can be as simple as stirring a soil sample with hydrochloric acid to dissolve potassium required... 

The study of all the forms of potassium in soils will no doubt be an important topic in the forthcoming volume on soil chemistry of the present encyclopedia. There have, however, been a reasonable number of laboratory studies on the extraction and availability of from feldspars and micas under varying conditions of temperature, pH and buffering, and over various particle-size ranges. A typical recent paper is that by Stohlberg [1959], and a recent summary of forms of potassium in the soil is that of Wiklander [1955]. The results of these studies can be very broadly summarized as follows. Potassium in feldspars is a major source of the potassium required for plant growth in many soils. It is, however, virtually nonexchangeable by comparison with the potassium in the micaceous clay minerals, and... 

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