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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Haematological data on children with mild iron deficiency-anaemia are compared with those of patients with heterozygous beta-thalassemia. The differential diagnosis of beta-thalassemia minor may suspected on the grounds of the blood smear. Confirmation of the diagnosis is based on the MCV, HbA2 and the graphic determination of EVR50 as well as by family survey. With these simple methods beta-thalassemia minor may be diagnosed with reasonable certainty even in the absence of a special laboratory for the determination of the beta-chain deficiency of hemoglobin. The importance of the correct differential diagnosis is stressed because of the danger of unnecessary iron therapy in thalassemia.
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PMID:[Erroneous diagnosis of iron deficiency anemia]. 248 26

Adenosine triphosphate (ATP) and adenosine diphosphate levels are decreased in erythrocytes from individuals with beta-thalassemia minor. Because 5-phosphoribosyl-1-pyrophosphate (PRPP) is an essential precurosr of adenine nucleotides, we tested the hypothesis that impaired PRPP synthesis is a mechanism for the decreased adenine nucleotide content. Erythrocyte PRPP synthetase activity was significantly decreased, and the Michaelis-Menten constant (Km) for ribose-5-phosphate (R5P) was significantly increased in individuals with alpha-thalassemia minor and those with beta-thalassemia minor. Intact erythrocytes from individuals with alpha-thalassemia and those with beta-thalassemia minor also had an impaired rate of PRPP formation. Both the decrease in PRPP synthetase activity and the impaired PRPP formation were also found in erythrocytes with microcytosis resulting from iron deficiency, indicating that these phenomena may not be specific to thalassemia minor. In all individuals examined, the rate of PRPP formation correlated with ATP content, suggesting that either (1) PRPP synthetase activity is a determinant of ATP content or (2) ATP content is a determinant of PRPP synthetase activity. The depletion of ATP from normal erythrocytes did not affect PRPP synthetase activity, suggesting that ATP content is not a determinant of PRPP synthetase activity. However, a decrease in PRPP synthetase activity did cause an impairment in the rate of adenine nucleotide synthesis, suggesting that PRPP synthetase activity is a determinant of ATP content. Taken together, our results suggest that the decrease in PRPP synthetase activity and the resulting impairment in the rate of PRPP formation are mechanisms for the decreased adenine nucleotide content in thalassemic erythrocytes.
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PMID:Decreased erythrocyte phosphoribosylpyrophosphate synthetase activity and impaired formation in thalassemia minor: a mechanism for decreased adenine nucleotide content. 254 52

The pathogenesis of hypochromic anaemia was studied in 138 Saudi bedouin infants aged 9 months. Approximately 25 per cent had hypochromic anaemia, but less than 10 per cent had serum ferritin levels indicative of iron deficiency. A few infants had heterozygous beta-thalassaemia, but many infants with hypochromic anaemia had normal haemoglobin A2 levels together with serum ferritin levels above 20 micrograms/l. DNA analysis of cord blood taken from the hospital where the infants were born showed that the frequency of the single alpha-globin gene deletion type (-alpha 3.7) of alpha-thalassaemia is 0.13 in the bedouin population of Western Saudi Arabia. alpha-Thalassaemia probably accounts for much of the anaemia previously thought to be due to iron deficiency in Saudi infants. Studies of iron status and estimation of the frequency of genetic causes of hypochromic anaemia are important when assessing the need for widespread nutritional programmes to prevent iron deficiency and in the interpretation of reference ranges of red cell indices in populations from malarial areas.
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PMID:The pathogenesis of hypochromic anaemia in Saudi infants. 260 83

The prevalence of probable homozygous alpha+ thalassaemia in Zimbabwe was found to be 3.25 percent in a survey of hospital patients (n = 2,000), 7.6 percent in a Batonga village (n = 66), and 5.3 percent in 16 kindreds (n = 94) investigated for iron overload. The diagnosis was based on finding a reduced mean cell volume (MCV), reduced mean cell haemoglobin (MCH), increased red cell count (RBC), and a normal Haemoglobin. These cases usually had a normal red cell distribution width (RDW), and of three discriminant functions tested the MCV2 x MCH was the most useful. Iron deficiency was excluded in the community based surveys. The importance of recognizing these changes is emphasized so that inappropriate iron therapy is not given.
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PMID:Homozygous alpha+ thalassaemia in Zimbabwe: an unrecognized cause of hypochromia and microcytosis. 261 73

Discriminant Functions (DFs), first described by Fisher in 1936, have been applied to the classification of microcytic disorders such as iron deficiency and heterozygous thalassemia. Mathematically DFs are weighted linear combinations of variables. If the underlying assumption of multivariate normality is valid DFs provide the best possible classification. Variables may need to be transformed before the DF is derived. When two groups have to be classified it is easy to visualise the DF. With one variable the DF is represented by the point which provides the best separation. In the bivariate situation the two groups form ellipses and the DF is the best line of separation whilst in the trivariate case the two groups are ellipsoids and a plane forms the best separation. Ratios and power functions are equivalent to DFs but they are less efficient and less rigorously derived. To apply DFs in hematological practice it is necessary to carefully select the measurements to be included and to define the case selection criteria. Once the DF has been derived it should be tested on a new data set and its transferability assessed. Like any single test the DF will have sensitivity and specificity which may need to be adjusted by changing the "cut-off" if the DF is used for screening rather than for differential diagnosis.
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PMID:Discriminant functions. 262 93

A new expert system developed on a Macintosh personal computer using a commercially available artificial intelligence shell was compared with four different discriminant functions (DFs) for the differentiation of microcytic anemia into etiologic categories. Several databases were used with a different composition but all contained at least some samples from thalassemic individuals and from patients with iron deficiency anemia. The DFs analyzed were those proposed by England and Fraser, Green and colleagues, Mentzer, and by Shine and Lal. None of the databases performed satisfactorily when used singly, whereas very high false-positive rates were obtained by one of them. The diagnostic efficiency was somewhat improved by combining several DFs. An expert system using an artificial intelligence "shell" with an "interference engine" was developed using cluster analysis and a set of learning examples. The input necessary for the system to achieve a conclusion consists of MCV, RBC, and RDW as well as a statement as to whether the patient has anemia. Based upon the values of these parameters, the expert system will give an "advice" regarding the probabilities for thalassemia, iron deficiency, and/or other probabilities such as previous transfusions, anemia of chronic disease, laboratory error, etc. In a prospective trial, the system functioned with an accuracy of better than 85%.
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PMID:The use of inference strategies in the differential diagnosis of microcytic anemia. 262 97

Presumptive distinction between iron deficiency and heterozygous thalassemia by analysis of the automated blood count and differential continues to be a challenge. We compared two proposed numerical discriminants (MCV2 x MCH, and MCV2 x RDW/100 x Hb) with an analytic microcomputer program (BCDE2 Lea & Febiger). In 7114 subjects, the numerical discriminants and the BCDE2 program correctly identified greater than 90% of thalassemia. In subjects with iron deficiency, the BCDE program was greater than 90% sensitive and specific for positive identification, while the numerical discriminants were less than 75% sensitive and specific at inferential identification. The numerical discriminants, BCDE2, and 17 experts in blood counting were asked to interpret the blood-count data in 7 fully-defined actual cases. The mean experts' score was 5.65 cases correct out of 7. The BCDE program was correct in all cases. The numerical discriminants could not analyze all cases, and both were incorrect in at least one case. We conclude that for the task of analyzing blood counts for microcytic disorders, microcomputer analysis by BCDE outperforms both numerical discriminant functions and analysis by expert hematologists.
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PMID:Distinction of microcytic disorders: comparison of expert, numerical-discriminant, and microcomputer analysis. 262 98

An Expert System (ES) approach to the assessment of thalassemia trait and iron deficiency was evaluated by transferring data from a Coulter S-Plus II Analyzer to an Apple II e computer. The discriminant rules of the algorithm were derived retrospectively from multivariate analysis of an existing data base. The parameters used were MCV, RDW, HGB, RBC, MPV, and PLT. Subsequently, the system has been evaluated for its ability to detect thalassemia and hemoglobinophathies in 1671 females and 1490 males in a real laboratory setting. The 845 cases of microcytosis among them were used to estimate the real frequencies of the diagnostic groups as identified by the ES (Micro Hema Screen). "On-Line" assessment of microcytosis may provide a quick method of acquiring and processing the data from an automated analyser. It can be applied in thalassemia and iron deficiency discrimination either as an intralaboratory primary assessment or as a population screening method.
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PMID:The performance characteristics of an expert system for the "on-line" assessment of thalassemia trait and iron deficiency--Micro Hema Screen. 262 99

Iron deficiency in pregnant women affected with beta-thalassemia minor and minima shows the need for prompt iron treatment. Some notes on the relationship between pregnancy and thalassemia are reported.
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PMID:[Iron therapy in patients with beta-thalassemia minor and minima in pregnancy]. 273 39

Alpha zero-thalassaemia of the British type is described for the first time in a New Zealand family. Microcytic, hypochromic red blood cells were found in affected individuals. Exclusion of iron deficiency and beta-thalassaemia suggested alpha-thalassaemia as a possible cause. This was confirmed by the detection of haemoglobin (Hb) H inclusion bodies. Definitive characterisation of the alpha-thalassaemia defect required DNA mapping which demonstrated the British alpha zero-thalassaemia deletion involving both alpha globin genes. alpha zero-thalassaemia should no longer be considered a disorder affecting individuals of Mediterranean or Asian backgrounds. Anglo-Saxons are also an at risk group. Co-inheritance of this abnormality with a second alpha-thalassaemia defect can lead to Hb H disease or Hb Bart's hydrops fetalis.
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PMID:British type alpha 0-thalassaemia in New Zealand. 273 65


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