By Dr. Mahmood Siddique, DO, FACP, FCCP, FAASM — Board-Certified in Internal Medicine, Pulmonary Medicine, Critical Care, and Sleep Medicine. Clinical Associate Professor, Rutgers Robert Wood Johnson Medical School.

The Number Your Doctor Gave You May Not Mean What You Think

Every week I see men who have been told their testosterone is normal. Some of them have been told this two or three times, by two or three different providers. And yet they sit across from me exhausted, foggy, disinterested in sex, and quietly convinced that something is wrong.

Most of the time, they are right.

The problem is rarely that testosterone was not tested. The problem is that it was tested incompletely — a single number drawn at the wrong time of day, interpreted against a reference range so wide it includes men who feel perfectly well and men who feel terrible, with no additional context.

If you are searching for a testosterone test near you in New Jersey, the most important thing I can tell you is this: the test itself is only as useful as the panel it sits in, and the panel is only as useful as the physician interpreting it.

Why Timing Matters Before the Blood Is Even Drawn

Testosterone is not a flat line. It follows a diurnal rhythm — meaning it rises and falls across the day in a predictable pattern. In most men, levels are highest in the early morning, typically between 7 and 10 AM, and lowest in the late afternoon and evening.

A testosterone reading taken at 2 PM on a man who is genuinely low can look deceptively normal. The same man tested at 8 AM might show a significantly different result.

In my practice, I always draw testosterone in the morning, on at least two separate occasions before making a diagnosis. A single afternoon result is not a diagnosis — it is a data point, and not a particularly reliable one.

This is standard practice in endocrinology. It is not universally followed in primary care or in many men’s health clinics that prioritise convenience over accuracy.

Total Testosterone — What It Measures and What It Misses

Total testosterone is the number most commonly reported. It measures all of the testosterone circulating in your blood — both the portion that is bound to proteins and the smaller portion that is free and biologically active.

The standard reference range in most laboratory reports runs from approximately 300 to 1000 ng/dL, with some labs setting the lower threshold as low as 264 ng/dL. This is an enormous range. A man at 310 ng/dL and a man at 950 ng/dL are both technically “normal” — but they are not in the same physiological condition, and they will not feel the same way.

The lower boundary of that range was largely derived from population studies that included elderly men and men with chronic illness. Using it as the sole benchmark for a 45-year-old who feels like he is running on empty is, in my view, a clinical shortcut.

I use total testosterone as a starting point. Not a conclusion.

Free Testosterone — The Number That Often Changes Everything

Here is what many men are never told: most of the testosterone in your blood is not actually available for your body to use.

Approximately 60% is tightly bound to a protein called sex hormone-binding globulin (SHBG). Another 38% is loosely bound to albumin. Only around 2% circulates as free testosterone — unbound, biologically active, and available to your tissues.

In men with high SHBG — which becomes more common with age, liver conditions, thyroid issues, and certain medications — total testosterone can look perfectly normal while free testosterone is critically low. These men have adequate hormone on paper and inadequate hormone in practice.

Free testosterone is not routinely ordered in many primary care settings. In my evaluation it is non-negotiable.

If your previous testosterone test did not include free testosterone and SHBG, you do not yet have a complete picture.

LH and FSH — Understanding Why Your Testosterone Is Low

Total and free testosterone tell me how much testosterone you have. LH and FSH tell me why.

Luteinising hormone (LH) is released by the pituitary gland and signals the testes to produce testosterone. Follicle-stimulating hormone (FSH) is involved in sperm production. Together they tell me where in the hormonal chain the problem originates.

If your testosterone is low and your LH is high, your pituitary is working correctly — it is sending the signal, but the testes are not responding. This is primary hypogonadism.

If your testosterone is low and your LH is also low or inappropriately normal, the problem is higher up — in the pituitary or hypothalamus. This is secondary hypogonadism, and it changes the diagnostic picture considerably. Secondary hypogonadism in a younger man warrants investigation for causes including sleep apnea, elevated prolactin, or a pituitary abnormality.

These distinctions determine treatment. They are also routinely missed when testosterone is the only thing tested.

Estradiol — The Most Overlooked Marker in TRT

Testosterone converts to estrogen through a process called aromatisation. In men, estradiol — the primary form of oestrogen — plays important roles in bone density, libido, cardiovascular health, and mood. Too little is a problem. Too much is also a problem.

When testosterone is elevated — whether through natural production or replacement therapy — estradiol can rise with it. Elevated estradiol in men causes fatigue, water retention, mood instability, reduced libido, and erectile difficulty. These are, of course, the same symptoms men start TRT to resolve.

I routinely check estradiol before initiating any testosterone therapy. I continue checking it throughout treatment. Estradiol management is one of the most clinically important and most commonly neglected aspects of TRT — and in my experience, it is the single most frequent explanation for why a man on TRT still does not feel well.