PCOS blood tests: what to get and what it means
Most women are diagnosed from an ultrasound and never have the metabolic side checked. This is the panel worth asking about, and when to do it.
The panel, and why each test is there
| Test | What it tells you | Timing |
|---|---|---|
| Fasting insulin | The single most useful PCOS test, and the one most often left out. Shows insulin resistance years before sugar becomes abnormal. | 8–12 hr fast |
| Fasting glucose | Paired with insulin to calculate HOMA-IR. Normal on its own for a long time. | 8–12 hr fast |
| HbA1c | Three-month average blood sugar. Good for tracking whether you are moving in the right direction. | Any time |
| Lipid profile | Triglycerides and HDL are often the first to shift in PCOS, and they guide which fats go into the plan. | 8–12 hr fast |
| TSH | Thyroid disorders sit alongside PCOS frequently and cause identical symptoms. Until this is correct, nothing else moves. | Any time, ideally morning |
| Total and free testosterone | Confirms the androgen component behind acne, hair growth and scalp thinning. | Day 2–5, morning |
| SHBG | Often low when insulin is high. Low SHBG means more active testosterone even when the total looks only mildly raised. | Day 2–5, morning |
| DHEAS | Checks whether the androgens are coming from the adrenal glands rather than the ovaries. | Morning |
| LH and FSH | The LH:FSH ratio is often raised in PCOS. Useful supporting evidence, no longer used to diagnose on its own. | Day 2–5 |
| Prolactin | Ruled out because a raised level causes irregular periods for an entirely different reason. | Morning, rested |
| AMH | Reflects the number of small follicles. Often high in PCOS, and increasingly used where ultrasound is not available. | Any day |
| Vitamin D | Deficiency is widespread in India, worsens fatigue and is linked with insulin resistance. | Any time |
| Vitamin B12 | Commonly low in vegetarians, and lower again on long-term metformin. | Any time |
| Haemoglobin and ferritin | Heavy or irregular bleeding depletes iron. This is often the real cause of the hair fall blamed on hormones. | Any time |
Getting the timing right
Two mistakes waste a lot of money at the lab:
- Hormone tests taken on the wrong cycle day. LH, FSH, testosterone and SHBG are read against day 2 to 5 reference ranges. Taken mid-cycle, the numbers are difficult to interpret. If your periods are very irregular or absent, ask your doctor when to go rather than guessing.
- Eating before the fasting tests. Insulin, glucose and lipids all need 8 to 12 hours without food. Plain water is fine. Tea with milk and sugar is not, and it will distort the insulin result — which is the most important number on the sheet.
Where possible, do the fasting metabolic tests and the day 2–5 hormone tests in the same visit by scheduling that visit for day 2 to 5, in the morning, fasting. One trip, one bill.
What each result changes on your plate
| Finding | What changes in the plan |
|---|---|
| High fasting insulin or HOMA-IR | Tighter carbohydrate structure, protein-led breakfast, fewer eating occasions, post-meal walking. See insulin resistance in PCOS. |
| Raised TSH | Thyroid treatment comes first, with medicine timing built into the plan. Weight loss stays slow until it is in range. See the thyroid diet plan. |
| Raised triglycerides, low HDL | Measured fats, more omega-3 sources, sharp reduction in refined carbohydrate and sugar. |
| Low vitamin D or B12 | Food sources plus supplementation decided by your doctor. Fatigue will not lift until these are corrected. |
| Low ferritin | Iron-rich foods with vitamin C to aid absorption, and tea or coffee kept away from meals. Hair fall usually traces back here. |
| HbA1c in the pre-diabetes range | The plan becomes a diabetes-prevention plan as well. See the diabetes diet plan. |
| Normal across the board | Still worth a structured plan. Cycle regularity and symptoms respond to eating patterns even when every number is normal. |
Tests you probably do not need
- Repeating the ultrasound every few months. The follicle picture changes slowly and rarely alters management.
- Expensive private “hormone panels” sold directly to consumers, which bundle dozens of markers that no one will act on.
- Food intolerance or “food sensitivity” IgG panels. These are not supported for this purpose and typically lead to needless restriction.
- Repeat testing every month. Insulin, HbA1c and lipids move over months, not weeks. Three to four months between repeats is reasonable.
Frequently asked questions
Which single test matters most if I can only afford a few?
Fasting insulin with fasting glucose, plus TSH. Those three cover the two things that most often drive symptoms and most often go unchecked.
My periods are irregular. How do I find day 2 to 5?
Day 1 is the first day of proper bleeding. If you have not bled for months, ask your doctor — they may test anyway or prescribe a withdrawal bleed first. Do not guess.
Do I need to stop my medicines before testing?
Ask the doctor who prescribed them. Hormonal contraceptives in particular alter testosterone and SHBG results substantially, so your doctor needs to know you are taking them when interpreting the report.
Can I do these tests while on my period?
Yes. Day 2 to 5 is during bleeding, and that is exactly when the hormone tests are meant to be done.
My reports are all normal but I have symptoms. What now?
Normal reports do not mean nothing is wrong. PCOS is diagnosed on a combination of cycles, symptoms and findings, and two of the three criteria are enough. Eating patterns, sleep and activity still change symptoms when the bloodwork looks unremarkable.
How often should I repeat them?
Typically every three to six months while actively working on it, then annually. Your doctor sets the interval based on what was found.
Have your reports and don’t know what they mean?
Send them across and Dt. Alka will build the plan around what they show.
WhatsApp Dt. AlkaFree PCOS self-checkPublished by Nourish with Dt. Alka, the clinical nutrition practice of Dt. Alka Pal, M.Sc. (Foods & Nutrition). General information only; which tests you need, and what your results mean, is for your doctor to decide. Related: PCOS diet plan, insulin resistance in PCOS, PCOS or PCOD.