Summary about Disease
Lactate dehydrogenase (LDH) deficiency is a rare genetic metabolic disorder that affects the enzyme lactate dehydrogenase. LDH plays a crucial role in energy production, specifically in the conversion of pyruvate to lactate. Different forms of LDH deficiency exist, depending on which subunit of the enzyme is affected (LDH-A or LDH-B). These deficiencies can primarily impact muscle function (LDH-A deficiency) or red blood cell metabolism (LDH-B deficiency). Most individuals with LDH deficiency have no obvious symptoms.
Symptoms
LDH-A Deficiency (Glycogen Storage Disease XI):
Muscle fatigue and pain, especially during strenuous exercise.
Exercise intolerance.
Muscle cramps.
Myoglobinuria (presence of myoglobin in urine, which can turn the urine dark red or brown) following strenuous exercise. This can potentially lead to kidney damage.
LDH-B Deficiency:
Usually asymptomatic.
May have mild hematological abnormalities (affecting red blood cells).
Causes
LDH deficiency is caused by mutations in the genes that code for the different subunits of the LDH enzyme.
LDHA gene mutations: Cause LDH-A deficiency (Glycogen Storage Disease XI)
LDHB gene mutations: Cause LDH-B deficiency These mutations are inherited in an autosomal recessive pattern. This means that an affected individual must inherit two copies of the mutated gene (one from each parent) to develop the disorder. Individuals who inherit only one copy of the mutated gene are carriers and usually do not exhibit symptoms.
Medicine Used
There is no specific cure for LDH deficiency. Treatment focuses on managing symptoms and preventing complications.
Dietary modifications: Some individuals may benefit from dietary adjustments to manage energy metabolism.
Supportive care: Managing muscle pain and fatigue is crucial.
Avoidance of strenuous exercise: Helps to prevent myoglobinuria and muscle damage, if LDH-A deficient.
Medications for kidney support: If kidney damage occurs due to myoglobinuria.
Is Communicable
No, LDH deficiency is not communicable. It is a genetic disorder caused by inherited gene mutations, not by an infectious agent.
Precautions
Genetic counseling: For individuals with a family history of LDH deficiency, genetic counseling is important to understand the risk of inheriting or passing on the mutated gene.
Avoid strenuous exercise: For individuals with LDH-A deficiency, avoiding strenuous exercise is the best way to prevent muscle breakdown and myoglobinuria.
Hydration: Staying well-hydrated can help to protect the kidneys, especially after exercise.
Medical alert bracelet: May be useful, especially for those with LDH-A deficiency, so that healthcare providers are aware of the condition in emergency situations.
Regular monitoring: Regular checkups with a doctor are recommended to monitor overall health and manage any symptoms.
How long does an outbreak last?
LDH deficiency is a chronic condition, not an outbreak. The symptoms can vary in intensity and may be triggered by exercise or other stressors. A bout of myoglobinuria can last from a few days to a week, depending on the severity.
How is it diagnosed?
Blood tests: Elevated creatine kinase (CK) levels in the blood may indicate muscle damage, particularly after exercise. In addtion, an LDH test can confirm that the amount of total LDH is not the issue; rather, the relative fraction of different LDH isoforms can point toward a defect in a specific LDH isoform.
Urine tests: Presence of myoglobin in the urine (myoglobinuria).
Muscle biopsy: In rare cases, a muscle biopsy may be performed to examine muscle tissue for abnormalities.
Genetic testing: Genetic testing to identify mutations in the LDHA or *LDHB* genes can confirm the diagnosis.
Exercise testing: Exercise testing with blood and urine sampling to measure LDH, CK, and myoglobin levels before and after exercise can reveal abnormalities in energy metabolism.
Timeline of Symptoms
The onset and progression of symptoms vary depending on the type of LDH deficiency.
LDH-A Deficiency: Symptoms typically appear during childhood or adolescence when individuals begin to engage in more strenuous physical activity. Symptoms are episodic and triggered by exercise.
LDH-B Deficiency: Often asymptomatic and may not be diagnosed unless investigated for other reasons.
Important Considerations
Differential Diagnosis: It's important to rule out other conditions that can cause muscle pain, fatigue, and myoglobinuria, such as other metabolic myopathies, rhabdomyolysis, and autoimmune disorders.
Genetic Counseling: Families with LDH deficiency should seek genetic counseling to understand the inheritance pattern and risks for future children.
Personalized Management: Management strategies should be tailored to the individual's specific symptoms and activity levels.
Research: As a rare disorder, ongoing research is needed to better understand the long-term effects of LDH deficiency and develop more effective treatments.
Awareness: Due to the rarity of the condition, raising awareness among healthcare professionals is important for prompt diagnosis and management.