The flipped pattern of LDH isoenzymes occur in –
**Core Concept**
The flipped pattern of LDH isoenzymes refers to the abnormal distribution of lactate dehydrogenase (LDH) isoenzymes in the blood, where the typical heart-type LDH-2 isoenzyme is elevated in tissues other than the heart. This occurs due to the presence of a specific enzyme, LDH-X, which is produced in certain types of cancer cells.
**Why the Correct Answer is Right**
The flipped pattern of LDH isoenzymes is typically seen in cases of metastatic cancer, particularly in the liver and lungs. This is due to the production of LDH-X, a variant of the LDH enzyme that is produced by cancer cells. The LDH-X enzyme has a different substrate specificity compared to the normal LDH enzyme, which allows it to accumulate in tissues other than the heart, leading to the flipped pattern of LDH isoenzymes. The LDH-X enzyme is produced in response to the stress of cancer cell growth and is thought to play a role in the development of cancer metastasis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the flipped pattern of LDH isoenzymes.
**Option B:** This option is incorrect because it is not a valid description of the LDH isoenzyme pattern seen in cancer.
**Option C:** This option is incorrect because it is not a condition that is associated with the flipped pattern of LDH isoenzymes.
**Clinical Pearl / High-Yield Fact**
The flipped pattern of LDH isoenzymes is a valuable diagnostic tool for identifying metastatic cancer, particularly in cases where the primary tumor is unknown. It is essential to remember that the presence of LDH-X isoenzyme is a specific indicator of cancer metastasis, and its detection can guide further diagnostic workup and treatment.
**Correct Answer:** C.