A diagnostic approach to patients with suspected lactose malabsorption

Lactose intolerance: An update on its pathogenesis, diagnosis, and treatment

Lactose intolerance has a high prevalence worldwide, ranging between 57% and 65%. It is caused by a reduction or loss of the activity of the intestinal enzyme lactase-phlorizin hydrolase, responsible for the digestion of lactose. This alteration determines an increased osmotic load in the small intestine and the fermentation of lactose by the bacterial flora, which leads to a high production of short-chain fatty acids and gas. This is followed by the onset of abdominal pain, diarrhea, and flatulence. In addition to these problems, it was found that subjects with lactose intolerance have an increased risk of developing various extra-intestinal diseases, including cancers. The diagnosis is essential to undertake an adequate treatment and, for this purpose, different methods have been tested. These include genetic test, hydrogen breath test (HBT), quick lactase test, and lactose tolerance test. HBT is the most used method because it is non-invasive, inexpensive, and highly sensitive and specific, as well as easy to perform. In clinical practice, the other methods are mainly used as HBT integration tests. There are also many therapeutic options. An appropriate intervention concerns the dietetic style, such as the consumption of lactose-free foods, but with nutritional characteristics comparable to dairy products. Other valid choices are represented by the use of exogenous enzymes, probiotics, prebiotics, the selection of milk containing specific types of beta-caseins. This review is intended to illustrate the diagnostic methods currently available and the possible therapeutic options for lactose intolerance.

Concordance between Lactose Quick Test, hydrogen-methane breath test and genotyping for the diagnosis of lactose malabsorption in children

BACKGROUND

Lactose intolerance is a frequent condition in certain populations. Different methods for diagnosis exist. There is scarce literature regarding Lactose Quick Test (LQT) and concordance with other methods for lactose intolerance diagnosis in children.

METHODS

Prospectively, we included children who underwent gastroduodenoscopy for evaluation of abdominal pain. We obtained a duodenal sample for LQT and blood sample for genetic test to evaluate LCT C>T_-13910 variant. Later, patients underwent breath test with lactose, to evaluate malabsorption. We evaluated the concordance between the three different tests.

KEY RESULTS

We included 46 patients, 56.5% women. Mean age was 13.2 years (range 9-18 years). 66.6% of patients had lactose malabsorption according to breath test; 64.4% were homozygous CC; and 91.3% had hypolactasia (mild or severe) according to LQT. None of the patients with normolactasia had altered breath test. Genetic test had a substantial agreement (k = 0.675) with breath test and fair agreement (k = 0.301) with LQT. LQT had fair agreement (k = 0.348) with breath test.

CONCLUSIONS & INFERENCES

Genetic test had better concordance with breath test than LQT to diagnose lactose malabsorption, however, none of the patients with normal LQT had lactose malabsorption. In patients who undergo gastroduodenoscopy to study abdominal pain, it seems reasonable to perform LQT, and, in those with hypolactasia, to perform breath test.

Hydrogen excretion in pediatric lactose malabsorbers: relation to symptoms and the dose of lactose

INTRODUCTION

Lactose malabsorption arises from lactase deficiency and may lead to lactose intolerance - gastrointestinal symptoms after lactose ingestion. Occurrence and severity of the symptoms are influenced by many factors, including the dose of lactose and the intensity of its colonic fermentation to short chain fatty acids and gases.

MATERIAL AND METHODS

The hydrogen breath test (HBT) after 30 g or 50 g of lactose was performed in 387 children. Further analysis included children who had a positive HBT result. The HBT parameters were net hydrogen concentration in each breath and total net hydrogen concentration during the HBT. The time of the first hydrogen rise was also calculated. HBT parameters were analyzed according to symptoms occurrence (lack or present), symptoms severity (lack, moderate or severe) and the dose of lactose (30 g or 50 g).

RESULTS

One hundred and six children (12.1 years, 46 boys) had a positive HBT result. Symptoms occurrence was positively related to net hydrogen concentration at 30 min, 60 min and 90 min (p < 0.001 at each time point), as well as to the total net hydrogen concentration (p < 0.001). There were no differences in hydrogen excretion between subjects with moderate and severe symptoms after lactose ingestion. Symptoms were more frequent in subjects given 50 g of lactose than in those given 30 g of lactose (79% vs. 47%, p = 0.003). In both dose groups symptoms occurrence was related to hydrogen excretion.

CONCLUSIONS

Symptoms occurrence is closely related to hydrogen excretion and to the dose of ingested lactose.

Lactose malabsorption in systemic sclerosis

BACKGROUND

There are no studies on systemic sclerosis (SSc) assessing the relationship between food intake, especially lactose, and gastrointestinal dysfunction.

AIM

To determine the prevalence of lactose malabsorption, using lactose breath test, in patients with SSc. To evaluate the correlation between lactose malabsorption and gastrointestinal involvement. To predict which SSc patients exhibit lactose malabsorption.

METHODS

Seventy-seven consecutive Caucasian patients with SSc and 20 control subjects underwent lactose breath test. All patients also completed a questionnaire on digestive symptoms, and a global symptom score (GSS) was calculated.

RESULTS

The prevalence of lactose malabsorption was higher in SSc patients than in controls (44.3% vs. 10%; P = 0.004). We observed a marked correlation between the presence of lactose malabsorption and: higher values of GSS (P < 0.0001); severe oesophageal (P = 0.018) and small intestinal (P = 0.04) motor disorders; and joint involvement (P = 0.019). Furthermore, in SSc patients with symptomatic lactose malabsorption, the median value of GSS of digestive symptoms was lower after initiation of lactose-free diet (P < 0.0001).

CONCLUSIONS

Our study underscores the fact that lactose malabsorption often occurs in patients with systemic sclerosis. Furthermore, our findings highlight the fact that lactose breath test is a helpful, noninvasive method, by identifying the group of patients with systemic sclerosis with symptomatic lactose malabsorption that may benefit from a reduction in lactose intake.

Clinical evaluation, biochemistry and genetic polymorphism analysis for the diagnosis of lactose intolerance in a population from northeastern Brazil

OBJECTIVE

This work aimed to evaluate and correlate symptoms, biochemical blood test results and single nucleotide polymorphisms for lactose intolerance diagnosis.

METHOD

A cross-sectional study was conducted in Fortaleza, Ceará, Brazil, with a total of 119 patients, 54 of whom were lactose intolerant. Clinical evaluation and biochemical blood tests were conducted after lactose ingestion and blood samples were collected for genotyping evaluation. In particular, the single nucleotide polymorphisms C>T-13910 and G>A-22018 were analyzed by restriction fragment length polymorphism/polymerase chain reaction and validated by DNA sequencing.

RESULTS

Lactose-intolerant patients presented with more symptoms of flatulence (81.4%), bloating (68.5%), borborygmus (59.3%) and diarrhea (46.3%) compared with non-lactose-intolerant patients (p<0.05). We observed a significant association between the presence of the alleles T-13910 and A-22018 and the lactose-tolerant phenotype (p<0.05). After evaluation of the biochemical blood test results for lactose, we found that the most effective cutoff for glucose levels obtained for lactose malabsorbers was <15 mg/dL, presenting an area under the receiver operating characteristic curve greater than 80.3%, with satisfactory values for sensitivity and specificity.

CONCLUSIONS

These data corroborate the association of these single nucleotide polymorphisms (C>T-13910 and G>A-22018) with lactose tolerance in this population and suggest clinical management for patients with lactose intolerance that considers single nucleotide polymorphism detection and a change in the biochemical blood test cutoff from <25 mg/dL to <15 mg/dL.