Howdy hard working praccies 🙂 well I received a very interesting email this week from someone asking me if I thought her urinary iodine result was accurate or if, as I have written about previously (https://rachelarthur.com.au/concentrating-concentration-getting-urinary-iodine-right/), it needed to be corrected for the creatinine content of her urine. Her raw iodine result was 24ug/L which suggests severe iodine deficiency. Her referring doctor however had also asked for creatinine and applied the creatinine correction formula I have previously described:
Iodine (mcg) ÷ Creatinine (mmol) X 8.85 = Corrected Iodine – which changed her result to 265 mcg/gCR which suggests she is NOT iodine deficient at all
She then asked another doctor to review the result who had told her 24ug/L was correct in the first place as ‘pathology companies automatically correct for the concentration of the urine’. Naturally the individual found the difference in opinions and results absolutely striking and ultimately disconcerting so she thought she’d ask me.
It was good to get this email because it made me go and check my facts, get in touch with all the major mainstream pathology companies we deal with and ask their labs ‘Do you or do you not automatically correct for creatinine when you report urinary iodine results?’ I was worried I had given you guys some bad advice 🙁 …here’s what I found out:
- Sullivan & Nicholaides Pathology (aka Douglass Hanly Moir, aka Melbourne Pathology, aka Clinpath in S.A.) – do NOT correct so you need to request for urinary iodine and perform the calculation yourself as above
- Healthscope Pathology – do NOT correct so you need to request for urinary iodine and perform the calculation yourself as above
- Laverty Pathology – do NOT correct so you need to request for urinary iodine and perform the calculation yourself as above
- S.A Pathology – do NOT correct so you need to request for urinary iodine and perform the calculation yourself as above
- QML Pathology – reportedly do automatically correct for iodine so you should not use the formula with results from this lab but take the result as is
Turns out some companies do correct for iodine but this is rare. If the pathology company you or your clients use is not on this list you should give them a call, ask to speak to the lab, the duty scientist or pathologist and ask them if they do correct automatically for creatinine when they report patients’ urinary iodine…because it can be the difference between 24 and 265 (!) and the right and the wrong conclusion! Hope this helps 🙂
Rachel has a bit of an obsession with iodine (!) & accordingly has recorded lots clinical pearls on this topic including a fascinating case study called Iodine Excess in Action. To download this Update in Under 30 Audio simply click here.