Lean body mass

Reports have appeared in the Hterature of the use of human growth hormone in older men. It has been proposed that a reduction in growth hormone in old age is responsible for increased adipose tissue, loss of lean body mass, and thinning of skin. Current studies conducted on older men indicate the hormone reverses these effects. In the parameters studied the patients resembled those of persons 10 —20 years younger (70). 

In order to define the obese state ia a clinical setting, it is necessary to have a means of estimating the amount of adipose (fat) tissue relative to lean body mass. Whereas highly accurate determiaations of body composition require complex laboratory procedures, large clinical studies typically employ measures of skia-fold thickness (11) or more commonly, body mass iadex (BMl) as a quantitative measure of obesity. 

Obesity is a difficult condition to treat. Dietary restriction of caloric intake is the first line therapy and is optimally combined with an exercise program to promote loss of fat relative to lean body mass (17). For the grossly obese (BMI > 40), invasive mechanical measures such as jaw wiring, gastric banding, and gastric by-pass have been attempted with at least limited success (18). 

Water makes up about 60% of the lean body mass of the human body and is distributed in two large compartments. 

CF patients have larger volumes of distribution of many antibiotics due to an increased ratio of lean body mass to total body mass and lower fat stores. CF patients also have an enhanced total body clearance, although the exact mechanism has not been determined. Increased renal clearance, increased glomerular filtration rate, decreased protein binding, increased tubular secretion, decreased tubular reabsorption, extrarenal elimination, and increased metabolism have all been proposed as possible reasons for the increased clearance. 

Reduced lean body mass Reduced muscle strength Reduced exercise performance Thin, dry skin cool peripheries poor venous access Depressed affect, labile emotions Impaired cardiac function... 

O Parenteral nutrition (PN), also called total parenteral nutrition (TPN), is the intravenous administration of fluids, macronutrients, electrolytes, vitamins, and trace elements for the purpose of weight maintenance or gain, to preserve or replete lean body mass and visceral proteins, and to support anabolism and nitrogen balance when the oral/enteral route is not feasible or adequate. 

Amino acids are provided to preserve or replete lean body mass and visceral proteins and to promote protein anabolism and wound healing. 

Amino acids are the building blocks of body proteins. There is no excess storage form of protein in the body, so amino acids are an essential component of the PN admixture. Amino acids are provided to preserve or replete lean body mass and visceral proteins and to promote protein anabolism and wound healing. Amino acids are a source of calories with a caloric value of 4 kcal/g. 

Massey and Opryszek9 elaborated further by showing that habitual caffeine consumption induced chronic hypercalcuria in young women (mean 24 years) after an oral caffeine challenge where they were fed either 300 mg of caffeine tablets per day or 6 mg caffeine per kilogram lean body mass (LBM) per day (range 274 to 325 mg/caffeine) mixed with decaffeinated coffee or tea when compared to a week of abstinence. Ad-... 

Fat/lean body mass T Vd lipid-soluble drugs... 

After oral ingestion, ethanol pharmacokinetics must take into account (1) Absorption from the gastrointestinal tract. Since ethanol is absorbed most efficiently from the small intestines, the rate of gastric emptying is an important factor that governs the rate of rise of blood alcohol concentration (BAC), i.e., the slope of the ascending limb of the BAC-time curve, and the extent of first pass metabolism of ethanol by the liver and stomach. (2) Distribution of ethanol in the body. Ethanol distributes equally in total body water, which is related to the lean body mass of the person, and (3) the elimination of ethanol from the body, which occurs primarily by metabolism in the liver, first to acetaldehyde and then to acetate [7]. 

BMI (and percentile of BMI) is only one factor in determining a person s weight-related health risk. Having a BMI in the healthy range does not necessarily mean that a person is fit and healthy. BMI does not take into account lean body mass or body frame. A muscular, large-framed person s BMI could indicate that he or she is obese, but other factors would show that this is not the case. 

In individuals who took thyroid hormones, 80% of the weight lost was lean body mass (muscle and bone) rather than excess fat. People taking these extracts experienced muscle weakness and bone breakdown, which led to a condition called osteoporosis, in which bones are weakened and the risk of bone fractures or breaks is increased. Thyroid hormone extracts also made the heart work harder by increasing metabolism, which led to problems such as increased heart rate, palpitations, and irregular heartbeat. These problems were potentially life threatening When the heart beats abnormally (or not at all), it is unable to pump blood and oxygen to the brain and body. Individuals die suddenly from this condition because the brain can only function for a few minutes without oxygen and nutrients. 

In order to avoid overdosing, estimated lean body mass should be used in obese patients. 

Physical examination should focus on assessment of lean body mass (LBM) and physical findings of vitamin, trace element, and essential fatty acid deficiencies. 

Visceral Proteins Used for Assessment of Lean Body Mass... 

Body composition 1 Total body water 1 Lean body mass T Body fat or i Serum albumin <-> or T -Acid glycoprotein (T by several disease states)... 

Drugs Use streptomycin at 15 mg/kg lean body mass intra-muscular every twenty-four hours for ten to fourteen days or use gentamicin at 5 mg/kg lean body mass intra-venous every twenty-four hours for ten to fourteen days or use gentamicin at 1.75 mg/kg lean body mass intra-venous every eight hours for ten to fourteen days or use ciprofloxacin at 400 mg intra-venous every twelve hours (oral therapy may be given at 750 mg orally every twelve hours after the patient is clinically improved, for completion of a ten to fourteen-day course of therapy) or use doxycycline at 200 mg intra-venous loading dose followed by 100 mg intra-venous every twelve hours (oral therapy may be given at 100 mg orally every twelve hours after the patient is clinically improved, for completion of a ten to fourteen-day course of therapy. 

When a drug has been absorbed it enters the systemic circulation and gets distributed throughout the body. The volume of distribution is the theoretical space in a patient that a substance occupies. This is influenced by the proportions of lean body mass versus fat. There is a decline in fat-free mass and body water, whereas there is an... 

There is a decrease in basal metabolic rate with a decline in lean body mass and less physical activity. The caloric requirement may, therefore, be reduced... 

The PK in the elderly is another subject of great interest to regulatory authorities. Although in most instances, unlike pediatric PKs, some linear extrapolations can be drawn on the basis of such parameters as lean body mass and age these should, nevertheless, be studies and validated. 

Clearance of nicotine is decreased in the elderly (age >65) compared to adults (Molander et al. 2001). Total clearance was lower by 23%, and renal clearance lower by 49% in the elderly compared to yonng adults. Lower nicotine metabolism in the elderly may be contribnted to by rednced liver blood flow, since no decrease in CYP2A6 protein levels or nicotine metabolism in liver microsomes due to age has been detected (Messina et al. 1997). No differences in steady-state nicotine plasma levels or estimated plasma clearance valnes were detected in three age gronps (18-39, 40-59, and 60-69 years) nsing patches with the same nicotine content (Gonrlay and Benowitz 1996). The volnme of distribntion of nicotine is lower in older snbjects due to a decrease in lean body mass (Molander et al. 2001). 

In contrast, undernourished normal subjects have a lower rate of energy expenditure than expected on the basis of their lean body mass. 

The obvious symptom of starvation is a loss of weight, which is most easily assessed by a decrease in the body mass index (BMI). Indeed, it is an excellent predictor of death from starvation. A value of BMI below about 13 in men and about 12 in women is not compatible with life. These values coincide with a loss of about 50% of lean body mass. The major causes of death from malnutrition in developed countries are pneumonia, other infections or heart failure. 

Obese patients Base dosage on an estimate of lean body mass. 

In recent years, several pilot clinical trials, assessing the elfects of GH administration to ageing adults, have been carried out. Typically, trial duration is 4-6 months. A 7% increase in lean body mass and skin thickness, along with a 14% drop in body fat, was observed in one trial, although results recorded in other trials were less striking. More detailed clinical trials and cost benefit analysis must be carried out in order to fully assess the potential of GH to counteract some of the elfects of ageing in the elderly population. 

However, the physiology of ageing includes poorer gastrointestinal absorption, somewhat reduced hepatic drug metabolism, and, commonly, a loss of lean body mass. While all of these have been documented, none is of as great a significance as the loss of renal excretory function which is invariably present in old age. 

Reduced total body water reduced lean body mass increased body fat... 

Anabolic steroids have been promoted as a means to foster protein synthesis and inhibit catabolism. Possibilities for considerable weight gain have been implied. In practice however these effects are disappointing, certainly in relation to the toxicity of these agents. In HIV-infected patients the administration of anabolic steroids appeared to result in a small increase in both lean body mass and body weight. The androgenic properties that all anabolic steroids have in common stand in the way of their therapeutic use. 

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