What is NICTH in Layman's Terms
NICTH (non-islet-cell-tumor hypoglycemia) is when a tumor—usually a large one—produces a substance that acts like insulin in your body, causing dangerously low blood sugar levels even though you're not diabetic and not taking diabetes medications. 1
How It Works
In simple terms, here's what happens:
- The tumor makes an abnormal protein called "big IGF-II" (insulin-like growth factor-II) that doesn't get processed correctly 1
- This protein sneaks into your tissues more easily than it should because it doesn't bind properly to its normal carrier proteins 1
- Once in your tissues, it acts like insulin, telling your body to pull sugar out of your bloodstream
- Your blood sugar drops, but your body's normal insulin is actually turned OFF (appropriately suppressed) 1
- This creates a confusing situation where you have low blood sugar without the usual cause (too much insulin)
Why This Matters in Your Case
In patients with metastatic breast cancer, NICTH is rare but recognized, particularly with certain breast tumor types like phyllodes tumors 2, 3, 4. The tumors are typically large and clinically apparent 1.
Key symptoms you might experience:
- Confusion, drowsiness, or mental fog (neuroglycopenia) 3
- Episodes typically occur when fasting or between meals 1
- Feeling shaky, sweaty, or weak when blood sugar drops
Important Distinction
Your levothyroxine (thyroid medication) does NOT cause this condition 5. NICTH is specifically caused by the tumor itself producing this abnormal IGF-II protein.
The Bottom Line
Think of NICTH as your tumor "hijacking" your body's blood sugar control system by making a fake insulin-like substance. Unlike diabetes where there's too much real insulin, here the tumor creates an impostor that fools your body into lowering blood sugar when it shouldn't.