Chapter 3 · Decoding the Alphabet Soup

ALT. AST. GGT. FIB-4. My lab report looked like someone had spilled a can of alphabet soup on the page. Every line had an abbreviation I didn't recognize, a number I couldn't interpret, and a reference range that seemed to exist just to make me feel stupid.

I'd been carrying the printout in my bag for three days, pulling it out in coffee shops and staring at it like it was a crossword puzzle in a language I hadn't learned yet. By Thursday, I decided it was time to learn the language.

The liver enzymes

Dr. Yamada had explained the basics at our first appointment, but I'd been too overwhelmed to absorb it all. This time, I came prepared — notebook out, questions written down, the look of a student who knows the exam is coming.

ALT (alanine aminotransferase) was the number that had started all of this. At 78 U/L, it was more than double the upper limit for men (33 U/L). ALT lives inside hepatocytes — the workhouse cells of the liver. When those cells are damaged or inflamed, ALT leaks into the bloodstream. The more damage, the more leakage, the higher the number.

"Think of it as a smoke detector," Dr. Yamada said. "ALT doesn't tell you how big the fire is. It tells you there's smoke."

My ALT being elevated meant hepatocytes were being injured. The most likely cause, given my ultrasound showing grade 2 steatosis: the fat itself was irritating the cells, causing low-grade inflammation. This was the boundary between simple fatty liver and NASH — non-alcoholic steatohepatitis, the inflammatory stage that carries real risk of progression.

AST (aspartate aminotransferase) is ALT's less specific cousin. It's also found in liver cells, but unlike ALT, it also lives in heart muscle, skeletal muscle, kidneys, and red blood cells. An elevated AST could mean liver damage — or it could mean you had a hard workout yesterday. Mine was 45 U/L (normal: under 40). Mildly elevated, consistent with the liver picture but not alarming on its own.

The ratio of AST to ALT matters too. In most cases of fatty liver disease, ALT runs higher than AST — an AST/ALT ratio below 1.0. When the ratio flips — AST climbing above ALT — it can signal more advanced disease or fibrosis. My ratio was 0.58, which was reassuring.

GGT (gamma-glutamyl transferase) rounds out the liver enzyme trio. GGT is elevated in a wide range of liver conditions and is particularly sensitive to alcohol-related damage. But it also rises with fatty liver, metabolic syndrome, and even obesity without overt liver disease. My GGT was 62 U/L (normal: under 55). Another signal pointing in the same direction.

Dr. Yamada showed me a graph — a kind of dashboard view of all three enzymes over time. "We'll track these every three months," he said. "The absolute numbers matter less than the trend. What we want to see is ALT coming down toward the 20s, and staying there."

The fibrosis question

The enzyme trio told us about inflammation — the current state of irritation in my liver. But they didn't answer the bigger question: had any permanent damage been done?

That's where FIB-4 came in.

FIB-4 — fibrosis-4 index — is a calculated score that estimates the likelihood of liver fibrosis. It uses four inputs:

Input	My Value
Age	42
AST	45 U/L
ALT	78 U/L
Platelet count	234 × 10⁹/L

The formula: (Age × AST) / (Platelet count × √ALT)

Plugging in my numbers: (42 × 45) / (234 × √78) = 1890 / (234 × 8.83) = 1890 / 2066 = 0.91

Dr. Yamada wrote the number on a sticky note and circled it. "Below 1.30 is low risk," he said. "You're at 0.91. That's good news."

FIB-4 Range	Risk Level	Next Step
Below 1.30	Low	Recheck in 1-2 years
1.30 – 2.67	Intermediate	Further testing (FibroScan or ELF panel)
Above 2.67	High	Hepatology referral, possible biopsy

My score — 0.91 — meant that significant fibrosis was unlikely. The fat was there, the inflammation was there, but the scarring hadn't started. Or at least, not enough to register on this index.

"This is the window," Dr. Yamada said. "Steatosis with inflammation but no significant fibrosis. This is when intervention has the most impact."

What the numbers don't tell you

I felt genuine relief looking at that 0.91. But Dr. Yamada was careful to temper it.

FIB-4 is a screening tool, not a diagnosis. It's excellent at ruling out advanced fibrosis — its negative predictive value is around 90%. But it has blind spots:

• It uses age in the numerator, which means it naturally climbs as you get older. For people under 35, it's considered unreliable. For people over 65, the low-risk cutoff is sometimes adjusted upward to 2.0.
• It estimates fibrosis, not steatosis. A low FIB-4 doesn't mean your liver isn't fatty — it means the scarring hasn't progressed. You can have substantial hepatic fat and a perfectly normal FIB-4.
• Acute inflammation — a liver flare, an infection, even a heavy drinking episode — can temporarily spike AST and ALT, artificially inflating the score.

"We'll recheck it in three months alongside your enzymes," Dr. Yamada said. "If it stays low and your ALT comes down, that's exactly what we want. If either number goes the wrong direction, we'll add a FibroScan."

Building my dashboard

That evening, I created a spreadsheet. Across the top: Date, ALT, AST, GGT, Platelets, FIB-4. Down the side: each lab draw, starting with today's numbers.

It felt like a small act of control — taking the alphabet soup and organizing it into something I could track, trend, and actually understand. The numbers weren't just clinical abstractions anymore. They were the score of a game I was now playing, whether I wanted to or not.

The enzymes told me about inflammation — the ongoing irritation in my liver that I could influence with diet, fasting, and movement. FIB-4 told me about structural damage — the scarring that I was trying to prevent. Together, they formed the feedback loop I'd need to know if my efforts were working.

Three months. That's how long I had until the next set of labs. Three months to learn how to eat differently, to try this thing called intermittent fasting, to see if the building metaphor Dr. Yamada had given me could survive contact with real life.

The numbers were on the screen. The trend line was mine to draw.