Nutritional Diseases Flashcards
Kwashiorkor’s
Depletes the visceral protein compartment
Serum albumin levels are very low - hypoalbuminemia - which causes generalized edema
Occurs when protein sufficiency is relatively more severe than total caloric deficit; occurs in first-born child when second child is born because first is weaned too early and fed a purely carbohydrate diet.
Weight loss masked by edema, so wasting is not as evident; other symptoms include hyper- pigmentation, areas of desquamation, flaky dermatosis, severe anemia, and hair changes.
LOSS OF APPETITE; MENTAL CHANGES; FATTY INFILTRATION OF LIVER.
Marasmus
Starvation with deprivation of all nutrients in proportion.
Depletes the somatic protein compartment because muscle proteins are used for fuel; fat is also used, rendering subcutaneous fat absent.
Serum albumin levels are either normal or only slightly reduced.
Extremities are emaciated, anemia, vitamin deficiencies, and possible immune deficiency, leading to concurrent infections. Wasting is quite evident.
Anorexia nervosa
Psychiatric disease with self-induced starvation due to obsession with thinness.
Highest death rate of any psychiatric disorder
Signs: amenorrhea, cold intolerance, bradycardia, constipation, and changes in skin and hair.
Major complication: increased susceptibility to cardiac arrhythmia and sudden death, resulting from hypokalemia.
Cachexia
A state of profound loss of lean body mass and fat due to cytokines, especially TNF.
Cancer is the most common cause, occurring in 50% of cases. Seen mostly in GI, pancreatic, and lung cancers.
Signs: extreme weight loss, fatigue, muscle atrophy, anemia, anorexia, and edema.
Major complication: Wasting eventually affects diaphragm and other respiratory muscles, leading to death.
Proteolysis-inducing factor
A mediator secreted by a tumor that tends the body toward cachexia. Causes skeletal muscle breakdown through the NF-kB-induced activation of the ubiquitin proteasome pathway, which breaks down myofibrils.
A glycosylated peptide excreted in the urine of weight-losing patients with pancreatic, breast, colon, and other cancers
Lipid-mobilizing factor
A mediator secreted by a tumor that tends the body toward cachexia. Causes skeletal muscle breakdown through the NF-kB-induced activation of the ubiquitin proteasome pathway, which breaks down myofibrils.
Increases fatty acid oxidation, TNF, and IL-6.
Vitamin A
Fat-soluble vitamin stored in liver
Functions: maintenance of normal vision, regulation of cell growth and differentiation, and regulation of lipid metabolism.
Deficiency => order of symptoms: 1) Xerophthalmia (dry eye); 2) Impaired vision, particularly at night; 3) Corneal ulceration; 4) Bitot spots, which are a buildup of keratin debris in small opaque plaques; 5) destruction of the cornea (keratomalacia) and blindness.
Secondary: Squamous metaplasia of mucous-secreting epithelium into a keratinized epithelium as well as loss of mucociliary epithelium of the airways
Healing affects: acne, psoriasis, acute promyelocytic leukemia, and neuroblastoma.
Bitot spots
Small opaque plaques that form on the eye due to a build-up of keratin debris that occurs with vitamin A deficiency.
Vitamin D
Fat soluble vitamin
Function: Maintains adequate plasma levels of calcium and phosphorous to support metabolic functions, bone mineralization, and neuromuscular transmission.
It also stimulates osteoblasts to synthesize the calcium-binding protein osteocalcin, involved in deposition of calcium during bone development. Vit. D is required to prevent rickets in children and osteomalacia in adults.
Process of metabolism: Vitamin D taken in from food or made endogenously with help of sun. DBP binds and takes it to liver. Vitamin D ==» 25-OH-D in liver, then most active form produced in kidney with conversion of
25-OH-D ==» 1, 25-dihydroxyvitamin D by 1-alpha-hydroxylase.
Regulation of 1,25-dihydroxyvitamin D in kidney
Hypocalcemia causes secretion of PTH, which activates 1-alpha-hydroxylase
Hypophosphatemia directly activates 1-alpha-hydroxylase
Negative feedback of 1, 25-dihydroxyvitamin D by itself - inhibits 1-alpha-hydroxylase
1, 25-dihydroxyvitamin D and calcium
Vitamin D stimulates intestinal absorption of calcium
Vitamin D encourages calcium reabsorption in the kidney
Vitamin D maintains saturated levels of calcium and phosphorous in the plasma. It works with PTH to induce osteoclasts to dissolve bone and release calcium and phosphorous into the circulation.
Who can make 1,25-dihydroxyvitamin D?
Macrophages, keratinocytes, and tissues such as breast, prostate, and colon.
Vitamin D and infections
Pathogen-induced activation of TLRs in macrophages causes increased expression of vitamin D receptor and CYP27B (vitamin D synthesizer in mitochondria), leading to vitamin D synthesis. Studies show that vitamin D can increase lymphocyte counts and enhance clearance of Mycobacterium tuberculosis.
Result of hypervitaminosis D
Children: metastatic calcification of soft tissues (kidney)
Adults: bone pain and hypercalcemia
POMC/CART neurons
provide the anorexigenic signal - the one that tells you you’re full.
Stimulated by leptin
These guys enhance energy expenditure and weight loss through the production of anorexigenic alpha-melanocyte-stimulating hormone (MSH), and the activation of melanocortin receptors 3, and 4. MSH and MC3/4R then produce TSH and CRH, which increase metabolic basal rate and anabolic metabolism, thus favoring weight loss.
Leptin
Secreted in response to abundant adipose tissue; travels to hypothalamus and stimulates the POMC/CART neurons while inhibiting the NPY/AgRP neurons.
Increases energy expenditure by stimulating physical activity, energy expenditure, and thermogenesis.
NPY/AgRP
provide orexigenic signals (the ones that tell you you’re hungry) and promote weight gain
Inhibited by leptin
These guys activate Y1/5 receptors in secondary neurons, which in turn release facts such as melanin-concentrating hormone (MCH) and orexin, which stimulate appetite.
Stable weight vs. inadequate weight ==> relationship to leptin
stable weight: POMC/CART and NPY/AgRP pathways are balanced
Inadequate stores of body fat: leptin secretion is diminished and food intake is increased.
