Prospective Comparison of Indirect Methods for Detecting Lactase Deficiency

Abstract

To compare sensitivity, specificity and convenience, four indirect methods of detecting lactase deficiency were tested prospectively in 25 subjects with biopsy-proved lactase deficiency and in 25 with normal lactase activity. After ingestion of 50 g of lactose, containing 1-14Clactose, breath hydrogen was abnormally elevated in all 25 lactase-deficient subjects (greater than 0.30 ml per minute at two hours); breath 14CO2 was below the normal range in 23, and in 19 the plasma glucose increased by less than 20 mg per deciliter. When lactose and ethanol were given together, the rise in plasma galactose remained less than 5 mg per deciliter in 24 of the lactase-deficient subjects. The specificity of the four tests was excellent, with only one false-positive plasma glucose test. Measurement of breath hydrogen is sensitive and specific, and does not require ethanol or isotopes. It is noninvasive, and is not influenced by gastric emptying or metabolic factors. We believe it to be the most suitable test for population screening for lactase deficiency.

Teste do H2 no ar expirado na avaliação de absorção de lactose e sobrecrescimento bacteriano no intestino delgado de escolares

“…A principal razão para a grande variação da atividade enzimática é o fato da produção da enzima ser determinada geneticamente, de modo recessivo autossômico, por um gene localizado no cromossomo 2 (15) . A lactase não é uma enzima indutível, sendo Reis JC dos, Morais MB de, Fagundes-Neto U. Teste do H 2 no ar expirado na avaliação de absorção de lactose e sobrecrescimento bacteriano no intestino delgado de escolares assim, alimentar-se com lactose não impedirá declínio da sua atividade, caso isto tenha sido determinado geneticamente (17,21,22) .…”

“…A investigação da má absorção de lactose tornouse mais simples com a utilização do teste respiratório de H 2 no ar expirado. Apesar de ser um método indireto, correlaciona-se bem com os níveis intestinais de lactase e apresenta boa sensibilidade e especificidade (17,27) .…”

“…Em seguida, foram aplicados os critérios de WATERLOW (32) Foram considerados maus absorvedores de lactose, os indivíduos que apresentassem incrementos de H 2 acima de 20 partes por milhão (ppm), em relação ao jejum (DH 2 ), em qualquer amostra coletada, após a ingestão de lactose (17) .…”

Distribution of the − 13910C>T polymorphism in the general population of Portugal and in subjects with gastrointestinal complaints associated with milk consumption

“…Lactose intolerance is usually investigated by indirect laboratory methods including breath hydrogen test (BH2T) (Newcomer et al 1975) or plasma glucose levels (Arola, 1994) after lactose ingestion.…”

Diagnosing lactase deficiency in three breaths

“…The lactose hydrogen breath test (H 2 -BT) has been used for more than 30 years, and is the preferred method to diagnose lactase deficiency in clinical practice (Newcomer et al, 1975). This test exploits the fact that, in contrast to human metabolism, the colonic flora metabolizes lactose into hydrogen (H 2 ), methane and short chain fatty acids.…”