Published: 18 Jun 2025

ICD9: 579.9      ICD10: K90.9      ICD11: 5C51.4Y

Okay, let's break down "Galactose malabsorption/intolerance, Galactosemia" to understand what it means.
These are related but distinct conditions involving the sugar galactose.

1. Galactose:

Galactose is a simple sugar, a monosaccharide.
It's one of the two sugars that make up lactose (the sugar in milk), the other being glucose. Lactose is a disaccharide (two sugars joined together).
When you digest lactose, your body breaks it down into glucose and galactose.
Galactose is also present in some fruits and vegetables.

2. Galactose Malabsorption/Intolerance:

Malabsorption: This means your body has difficulty absorbing galactose from the digestive tract into the bloodstream.
Intolerance: This is the result of malabsorption. Because the galactose isn't absorbed properly, it stays in the gut, where bacteria ferment it. This fermentation produces gas, acids, and other substances that cause symptoms.
Causes: Galactose malabsorption/intolerance is usually due to a deficiency or malfunction of the SGLT1 transporter. SGLT1 is a protein in the small intestine responsible for absorbing both glucose and galactose. Damage to the gut lining, certain medications, or genetic factors can lead to reduced SGLT1 function.
Symptoms:
Bloating
Gas
Abdominal pain or cramps
Diarrhea
Nausea

Diagnosis: Usually involves a process of elimination based on symptoms and potentially a hydrogen breath test after galactose consumption.
Treatment: The primary treatment is a low-galactose diet. This means avoiding or limiting foods high in lactose (milk, cheese, yogurt, ice cream) and foods containing free galactose. The degree of restriction depends on the individual's tolerance level.

3. Galactosemia:

This is a serious, rare, genetic metabolic disorder. It's very different from galactose malabsorption/intolerance.
Cause: Galactosemia occurs when the body cannot properly process (metabolize) galactose. This is due to a deficiency in one of the enzymes needed to convert galactose into glucose. The most common type is caused by a deficiency of the enzyme galactose-1-phosphate uridylyltransferase (GALT). Other, rarer forms are caused by deficiencies in galactokinase (GALK) or UDP-galactose 4-epimerase (GALE).
What happens: When galactose cannot be broken down, it builds up in the blood and tissues. This buildup can cause serious health problems.
Symptoms (in infants): Galactosemia is usually detected in newborn screening tests. Symptoms often appear within the first few days or weeks of life if the baby consumes milk or formula containing lactose. Symptoms include:
Jaundice (yellowing of the skin and eyes)
Vomiting
Diarrhea
Lethargy (excessive sleepiness)
Poor feeding
Failure to thrive (not gaining weight and growing properly)
Enlarged liver (hepatomegaly)
Cataracts (clouding of the lens of the eye)
Intellectual disability (if untreated)
Increased susceptibility to infections
In severe cases, liver failure, sepsis, and death
Diagnosis: Newborn screening is standard in many countries. If the screening is positive, further enzyme testing is done to confirm the diagnosis.
Treatment: The main treatment for galactosemia is a strict galactose-free diet, starting as soon as possible after diagnosis. This means avoiding all milk and milk products, as well as other foods that contain galactose. Special formulas made from soy or other non-dairy sources are used for infants. Lifelong dietary management is essential. Even with a strict diet, some long-term complications may still occur.
Complications (even with treatment):
Speech problems
Learning disabilities
Motor skill delays
Ovarian failure in females

Key Differences Summarized:

| Feature | Galactose Malabsorption/Intolerance | Galactosemia |
| -------------------- | ------------------------------------- | ----------------------------- |
| Nature | Digestive problem | Genetic metabolic disorder |
| Cause | SGLT1 Transporter issue | Enzyme deficiency (usually GALT) |
| Severity | Uncomfortable, but generally not life-threatening | Very serious, potentially life-threatening if untreated |
| Onset | Can develop at any age | Present from birth |
| Symptoms | Primarily digestive (bloating, gas, diarrhea) | Wide range of systemic problems (jaundice, vomiting, liver damage, etc.) |
| Diagnosis | Symptom-based, hydrogen breath test | Newborn screening, enzyme tests |
| Treatment | Low-galactose diet | Strict galactose-free diet |

In simpler terms:

Galactose malabsorption/intolerance: Your body has trouble *absorbing* galactose, causing digestive upset. Think of it like lactose intolerance, but specifically for galactose.
Galactosemia: Your body can't *process* galactose at all because it's missing a crucial enzyme. This leads to a buildup of galactose, which poisons the body.

It's important to consult with a doctor or registered dietitian for accurate diagnosis and personalized management of either condition. They can provide guidance on appropriate dietary changes and monitoring.