What is the cause of glucosuria without diabetes mellitus (DM) in a 23-year-old female with a body mass index (BMI) of 16, indicating underweight status?

From the Guidelines

Glucosuria without diabetes in a 23-year-old female with a BMI of 16 is most likely due to a rare genetic disorder, such as glycogen storage disease type I (GSD I), which can cause renal damage and impaired glucose reboathing, rather than a benign condition like renal glucosuria. The patient's low BMI and potential for malnutrition or an eating disorder are also concerning and require immediate attention 1. A comprehensive evaluation including nutritional assessment, screening for eating disorders, and monitoring of electrolytes and other metabolic parameters is essential.

Key Considerations

• The patient's symptoms and laboratory results should be evaluated to determine if they have GSD I or another rare genetic disorder, with consideration of molecular genetic testing, enzymology, and/or liver biopsy tissue 1.
• Laboratory tests should include fasting blood glucose, HbA1c, renal function tests, urinalysis, and liver function tests to confirm the diagnosis and rule out other conditions.
• A multidisciplinary team including a dietitian, psychiatrist, and geneticist should be involved in the patient's care to address potential malnutrition, eating disorders, and genetic counseling.
• Regular follow-up is recommended to monitor both the glucosuria and the patient's nutritional status, as well as to screen for potential long-term complications of GSD I, such as liver adenomas, hepatocellular carcinoma, and renal glomerular dysfunction 1.

Potential Complications

• GSD I can cause a range of complications, including hepatomegaly, liver adenomas, hepatocellular carcinoma, bleeding diathesis, anemia, vitamin D deficiency, osteoporosis, and renal glomerular dysfunction 1.
• The patient's low BMI and potential for malnutrition or an eating disorder can also increase the risk of complications, such as electrolyte imbalances, osteoporosis, and cardiovascular disease.
• Early recognition and treatment of GSD I and related complications can improve outcomes and quality of life for the patient 1.

From the Research

Possible Causes of Glucosuria without Diabetes Mellitus

• Renal glycosuria: a benign condition characterized by the presence of glucose in the urine despite normal blood glucose levels 2, 3, 4, 5
• Familial Renal Glucosuria (FRG): a genetic disorder caused by mutations in the SLC5A2 gene, leading to impaired renal glucose reabsorption and glucosuria 3, 4, 5
• Low renal threshold for glucose excretion: a condition where the kidneys excrete glucose at a lower blood glucose level than normal, resulting in glucosuria 4

Factors Associated with Glucosuria without Diabetes Mellitus

• Younger age: patients with renal glycosuria tend to be younger than those with other forms of glucosuria 5
• Lower body mass index (BMI): patients with renal glycosuria often have a lower BMI than those with other forms of glucosuria 5
• Genetic mutations: mutations in the SLC5A2 and HNF1A genes have been associated with renal glycosuria 4, 5

Diagnosis and Evaluation

• Urinalysis: to detect the presence of glucose in the urine 2, 6
• Oral glucose tolerance test: to assess the body's ability to regulate blood glucose levels 2
• Measurement of renal threshold for glucose excretion: to evaluate the kidneys' ability to reabsorb glucose 4
• Genetic testing: to identify mutations in the SLC5A2 and HNF1A genes associated with renal glycosuria 4, 5