Frequency of primary and secondary lactose intolerance in dyspeptic adult population and comparison based on age of onset,duration and Sex

Objectives: the objectives of this study were to find out the frequency of primary and secondary lactose intolerance in adult population attending outpatient department and to compare them in terms of age of onset,duration and sex. methods: hundred adults aged between 18-60 years of both sexes presented with diarrhea,abdominal distension or bloating,abdominal cramps,nausea or vomiting and altered bowel habits were included. those with inadequate pretest fasting within 12 hours,smoked recently,used antibiotics within 2 weeks prior to hydrogen breath test and with lung disorders were excluded. hydrogen breath test employing hydrogen breath analyzer (bedfont scientific limited,uk) was used to determine the lactose intolerance. during this test hydrogen level in exhaled air was measured by using hydrogen breath analyzer after administration of 50 gm dose of lactose in 250 ml of water at 30 minutes interval for 2-3 hours. results: intolerance of lactose was observed in 40% patients. among those lactose intolerant patients,80% were found to have primary lactose intolerance and 20% were found to have secondary lactose intolerance. the common causes of secondary lactose intolerance were celiac disease in 87.5% patients and bacterial overgrowth in 12.5% patient. the frequency of age of onset among primary lactose intolerance aged 15-30 years,31-45 years and 46-59 years were 20%,25% and 35%,whereas the corresponding figures for secondary lactose intolerance were 2.5%,15% and 2.5% respectively. the duration of symptoms among primary lactose intolerance patients from 1-5 years,6-10 years,11-15 years and 16-20 years was 50%,22.5%,5% and 2.5% whereas the corresponding figures for secondary lactose intolerance were 10%,5%,2.5% and 2.5% respectively. conclusion: this study revealed that the frequency of primary lactose intolerance was significantly high among higher age groups p < 0.05 and the commonest cause of secondary lactose intolerance was celiac disease.