Anemias microcytic

Macrocytic anemias Megaloblastic anemias Vitamin B12 deficiency Folic acid deficiency anemia Microcytic hypochromic anemias Iron-deficiency anemia Genetic anomaly Sickle cell anemia Thalassemia... 

A. Iron and Vitamin Deficiency Anemias Microcytic hypochromic anemia, caused by iron deficiency, is the most common type of anemia. Megaloblastic anemias are caused by a deficiency of vitamin B, or folic acid, cofactors required for the normal maturation of red blood cells. Pernicious anemia, the most common type of vitamin Bj, deficiency anemia, is caused by a defect in the synthesis of intrinsic factor, a protein required for efficient absorption of dietary vitamin B 2, or by surgical removal of that part of the stomach that secretes intrinsic factor. 

In a second type of thalassemia the synthesis of specific non-a-chains is impaired. The heterozygous form of 3-thalassemia is characterized by a mild hypochromic microcytic anemia, by an increased level of Hb-A2 (4 to 7 percent), and, in the majority of the cases, by an elevated Hb-F (1 to 15 percent). 

Evaluating the mean corpuscular volume (MCV) is the next step in an anemia work-up. It is classified as microcytic, normocytic, or macrocytic if the MCV is below, within, or above the normal range of 80 to 96 fIVcell, respectively. 

Morphologic classifications are based on cell size. Macrocytic cells are larger than normal and are associated with deficiencies of vitamin B12 or folate. Microcytic cells are smaller than normal and are associated with iron deficiency whereas normocytic anemia may be associated with recent blood loss or chronic disease. 

Severe hypochromic microcytic anemia, responding only to vitamin B6 and not to iron, a typical symptom of B6 deficiency in many species of animals, is related to the dependence of porphyrin biosynthesis on vitamin Be, preceding the 8-aminolevulinic acid stage, at the condensation of glycine with succinate to yield a-amino- 3-ketoadipate, the immediate precursor of 8-aminolevulinic acid. 

A 75-year-old woman is seen in the emergency room with a fractured arm. Physical examination revealed multiple bruises and perifollicular hemorrhages, periodontitis, and painfid gums. Her diet consists predominately of weak coffee, bouillon, rolls, and plain pasta. Lab results indicated mild microcytic anemia. Which of the following enzymes should be less active than normal in this patient ... 

The last enzyme in the pathway, heme synthase (ferrochelatase), introduces the Pe into the heme ring. Deficiency of iron produces a microcytic hypochromic anemia. 

Lead inactivates many enzjnnes including ALA dehydrase and ferrochelatase (hetne synthase), and can produce a microcytic sideroblastic anemia with ringed sideroblasts in the bone marrow. Other symptoms include ... 

A 62-year-old man being treated for tuberculosis develops a microcytic, hypochromic anemia. Ferritin levels are increased, and marked sideroblastosis is present. A decrease in which of the following enzyme activities is most directly responsible for the anemia in this man ... 

Answer A. Pregnant woman with megaloblastic anemia and elevated serum homocysteine strongly suggests folate deficiency. Iron deficiency presents as microcytic, hypochromic anemia and would not elevate homocysteine. deficiency is not most likely in this presentation. 

Few studies have reported toxicological effects of 1,4-dichlorobenzene in children. Campbell and Davidson (1970) reported a case of a 21-year-old woman eating 1-2 toilet air-freshener blocks per week while pregnant. The mother developed hematological aberrations (hypochromic, microcytic anemia. 

Cell multiplication is inhibited because DNA synthesis is insufficient. This occurs in deficiencies of vitamin Bu or folic acid (macrocytic hyperchromic anemia). 2. Hemoglobin synthesis is impaired. This situation arises in iron deficiency, since Fe + is a constituent of hemoglobin (microcytic hypochromic anemia). 

Lead poisoning produces a microcytic anemia that arises from the abiiity of iead to biock erythro-poiesis by inhibiting heme synthesis in the bone marrow at two steps. 

The answer is C. The patient s symptoms represent a composite of neurologic and gastrointestinal dysfunction, which are consistent with the anemia that is due to lead poisoning. Testing for lead would be appropriate for the patient, the other members of the household, and the house itself. Inorganic lead produces the microcytic anemia by inhibition of heme synthesis in erythropoietic cells of the bone marrow. All the other options represent enzymes of heme synthesis or degradation, but none of them are affected by lead. 

Measuring the child s blood lead level will be very useful in assessing the possibility of lead poisoning. There is evidence that at blood lead levels of about 10 Jig/dL, children are at risk for developmental impairment. Other tests that may be useful include examination for microcytic anemia and erythrocyte stippling and radiographic examination of the long bones for lead lines. 

The answer is d. (Hardman, pp 1331-1333.) Iron-deficiency anemia usually occurs in infants undergoing rapid growth. In adults in a late stage, it may result in a bowel syndrome associated with gastritis and hypochlo-rhydria (Plummer-Vinson syndrome). Characteristically, all iron-deficiency anemias are associated with a hypochromic microcytic blood profile. Infestation with the tapeworm D. latum is accompanied by a hyperchromic macrocytic anemia, which is treatable with vitamin B12. Bleeding syndromes are treated with iron. 

Porphyrins in the erythrocytes, are measured to diagnose erythropoietic protoporphyria. This determination may also be useful to differentiate between different causes of microcytic anemia. 

Hematological Effects. Hematological effects have not been observed in humans or animals with normal renal function. However, microcytic, hypochromatic anemia has been observed in individuals with impaired renal function. The anemia is unresponsive to iron therapy. The severity of the anemia correlates with plasma and erythrocyte aluminum levels and can be reversed by terminating aluminum exposure and chelation therapy with DFO. 

The major population at risk for aluminum loading and toxicity consists of individuals with renal failure. In a study by Alfrey (1980), 82% of nondialyzed uremic patients and 100% of dialyzed uremic patients had an increased body burden of aluminum. The decreased renal function and loss of the ability to excrete aluminum, ingestion of aluminum compounds to lessen gastrointestinal absorption of phosphate, the aluminum present in the water used for dialysate, and the possible increase in gastrointestinal absorption of aluminum in uremic patients can result in elevated aluminum body burdens. The increased body burdens in uremic patients has been associated with dialysis encephalopathy (also referred to as dialysis dementia), skeletal toxicity (osteomalacia, bone pain, pathological fractures, and proximal myopathy), and hematopoietic toxicity (microcytic, hypochromic anemia). Pre-term infants may also be particularly sensitive to the toxicity of aluminum due to reduced renal capacity (Tsou et al. 1991)... 

Hypoproteinemia may result in low levels of serum calcium, ceruloplasmin, and transferrin. Because losses of iron are at most 0.5-1.0 mg/24 hr, even with the heaviest proteinuria, other factors must operate to produce iron deficiency and microcytic hypochromic anemia. Although the copper-binding protein ceruloplasmin is lost in the urine in nephrotic subjects and its plasma levels are low, plasma and red cell copper concentrations are usually normal. Zinc circulates mainly bound to albumin and also to transferrin, and thus the reported reduction zinc concentration in plasma, hair, and white cells in nephrotic patients is not surprising. 

Proton pump inhibitors Low threshold in the cases of previous gastric problems (e.g., ulcers, diaphragmatic hernias) and in the cases of microcytic anemia of unknown cause... 

Iron is stored in intestinal mucosal cells as ferritin (an iron/protein complex) until needed by the body. Iron deficiency results from acute or chronic blood loss, from insufficient intake during periods of accelerated growth in children, or in heavily menstruating or pregnant women. Therefore it essentially results from a negative iron balance due to depletion of iron stores and inadequate intake, culminating in hypochromic microcytic anemia. Supplementation with ferrous sulfate is required to correct the deficiency. Gastrointestinal disturbances caused by local irritation are the most common adverse effects caused by iron supplements. 

Slow, relatively low exposure accumulation of Al over a period of years can lead to a number of clinical manifestations, some of which seem to be bypassed in acute Al encephalopathy due to extremely high exposure to Al. Al encephalopathy is a clinical syndrome and, as can be seen in Table 5, there are similarities and differences in the neurological symptoms of acute and chronic Al encephalopathy. In chronic Al encephalopathy microcytic anemia [41, 93, 95—98] and EEG changes [99-104] can precede clinical symptoms [105]. It is unknown if these symptoms can also precede the clinical symptoms of acute encephalopathy. In contrast to acute Al encephalopathy, where speech disturbances are absent, speech disorders are an important presenting clinical sign of neurotoxicity in chronic Al encephalopathy. The neurological basis of the speech apraxia is obscure but it appears to have elements of dysarthria and dysphasia [33, 73], The initial... 

One of the most confusing features of Al encephalopathy is the lag phase between exposure and clinical symptoms and the subsequent rapid course of the disease. The delay can be months to years in the classical form and several weeks in the acute form. Because patients are generally symptom-free or demonstrate minor symptoms like microcytic anemia, physicians are unaware of the exposure until the development of severe symptoms. Until recently it was not known that a relatively short dialysis related exposure time to Al can be fatal. 

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