Thyroid UK
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Serum Inorganic Phosphate

Is anyone able to tell me a bit more about whether an out of range Serum inorganic phosphate result of 1.7 (range 0.8 - 1.50 mmol/l) is any cause for concern please?

I think I could have hashimotos as I tested positive for anti thyroid peroxide (350.1 U/mL) and have a goiter. TSH, FT3 and FT4 all currently within range though. I am not on any medication.

My doctor said all my bloods are normal except the antibodies, but I asked for a printout and noticed myself this out of range serum inorganic phosphate. Naturally I have googled to find out a bit, but would appreciate any pearls of wisdom from anyone on here!

Thanks for your help.

4 Replies

I just looked at this blood test (not the urine test, right?). Did you refrain from eating anything before the test? Do you drink soda pop as I know it has a lot of phosphorus. I don't know how serious this is but it is a very narrow range. Did you have a calcium deficiency along with this test?

You would be diagnosed with Hashimoto due to your antibodies and perhaps you are still in the normal range but they may not be normal for you. Could you post your thyroid tests?

Higher than normal levels of phosphorus (hyperphosphatemia) may be due to or associated with:

Kidney failure

Hypoparathyroidism (underactive parathyroid gland)

Hypocalcemia (abnormally low levels of calcium)

Diabetic ketoacidosis (when first seen)

Phosphate supplementation


Thanks for taking the time to reply Heloise,

That's right it was a blood test. It wasn't a fasting test although I hadn't eaten anything directly before it. I only very occasionally drink soda pop/ fizzy drinks.

My thyroid test results are:

TSH 2.97 (range 0.35 - 4.94)

FT4 11.6 (range 9.01 - 19.05)

FT3 5.10 (range 2.63 - 5.70)

Serum Calcium is within range at 2.41 (range 2.1 -2.55)

Another blood test which is within range but at the lowest end is Serum Sodium 137 (range 136 - 145).

Perhaps the inorganic phosphate being out of range really isn't an issue and that's why the doctor didn't mention it, I just posted on here to see if anyone knows more!

Thanks for your help.


Ali, it was probably due to something you ate then. But aren't you somewhat concerned about your high TSH and low T4 and the antibodies?


Hi Heloise,

Yes, I am feeling quite unwell at the moment, with what I think are hypothyroid symptoms, but in my GP's eyes the TSH and FT4 are 'normal' as they fall within the ranges. To be fair I guess my FT3 does look quite good. Thankfully my GP is writing to an endocrinologist to ask for advice due to my antibodies, goitre, and other symptoms. I just have to wait patiently in the meantime. As this phosphate reading was out of range I thought I would ask on here about it in case someone else knew something about it and I could alert my GP to it being out of range to see if that would speed things up.

Thanks again



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