PERFORMANCE
BLOOD TESTING,
because normal isn't always best.

Total testosterone on its own can be misleading. Most of it is bound to SHBG and albumin and is not available to your tissues. This panel measures all three so a free testosterone figure can be calculated, which is the portion actually able to act.

Men wanting to understand low energy, poor recovery, reduced strength, low mood or reduced sex drive. Also used by anyone tracking the effect of training load, sleep or body composition over time.

In the morning, before 10am. Testosterone follows a daily rhythm and is highest earlier in the day, so an afternoon sample can read low in someone whose levels are fine.

Ferritin reflects how much iron you have in storage. It falls before haemoglobin does, so iron can be running low well before a standard blood count would flag anything.

Anyone training regularly who feels flat, is slower to recover than usual, or is short of breath on efforts that used to feel manageable. Common in endurance athletes, in women with heavy periods, and in people eating little or no red meat.

Ferritin rises with inflammation and after hard training, so avoid sampling within 48 hours of a hard session or while unwell. Otherwise any day is suitable.

Vitamin D is made in the skin from sunlight and is involved in bone strength, muscle function and immune function. At UK latitudes there is not enough sunlight to make it from around October to March, so levels fall over winter regardless of how much time you spend outdoors.

Anyone wanting to know where they stand before winter, anyone already supplementing who wants to see whether the dose is doing anything, and anyone who trains indoors or covers up outdoors.

Any day, any time. If you are taking a supplement, do not stop before testing. The point is to see what your current routine is producing.

B12 is needed for red blood cell production and nerve function. The body cannot make it, and it comes almost entirely from animal foods, so intake matters. The active form is the portion your cells can actually use, which makes it a more sensitive measure than total B12.

People eating plant based or largely plant based diets, anyone with unexplained fatigue or pins and needles, and anyone taking a B12 supplement who wants to see whether it is being absorbed.

Any day. Recent supplement doses raise the reading. Speak to your doctor before pausing anything you have been prescribed.

FSH and LH are released by the pituitary gland to stimulate the ovaries, and tend to rise as the ovaries become less responsive. Oestradiol falls over time but fluctuates considerably during perimenopause. TSH and free thyroxine are included because thyroid problems are common in midlife and cause many of the same symptoms.

Women noticing hot flushes, night sweats, irregular periods, broken sleep, low mood, anxiety, difficulty concentrating or persistent fatigue. Also worth considering under 45, or where there is a family history of early menopause.

With a reasonably regular cycle, sample between days 2 and 5, counting the first day of proper bleeding as day 1. Day 3 is best. If your cycle is irregular or has stopped, any day is suitable. Morning samples are preferred.

This test does not diagnose perimenopause. Hormone levels swing considerably at this stage, so one set of results can look unremarkable in someone who is clearly perimenopausal. Over 45, perimenopause is usually recognised from symptoms and cycle changes rather than blood results.

The broadest finger-prick panel of the six. It covers the four things most commonly behind persistent tiredness that rest does not fix: iron status, thyroid function, vitamin D and background inflammation.

Anyone whose energy has dropped without an obvious explanation, or who is training but no longer recovering between sessions. A sensible starting point when you do not yet know which direction to look in.

In the morning where possible. Avoid sampling within 48 hours of a hard training session or while unwell, since both raise hs-CRP and ferritin and make the picture harder to read.