How beneficial are blood tests?
Are they usually ordered if scratch tests are positive, or negative?
My environmental scratch tests were all negative. Doctor recommended I get the blood test for cat, to be certain. (I think he said the blood test tests for something different?)
He also wanted me to get blood test for peanuts and sesame seeds. I will be seeing him in about a month to get results of this blood test and will discuss then.
But, even if they test negative I'm not going to feel safe eating those things. In other words, I'm not betting my life on a test. Would I be reasonable in wanting a food challenge if the tests are negative?
DH, who has witnessed most of my reactions is opposed to me doing this.
I assume they'd do food challenges if the tests were negative.
It's not only reasonable, it's typical—at least in the US.
We've done both skin and blood tests for DS and myself historically. DS also had the component test for peanut, and if you have the option, I'd get that. It's so much more informative.
For me last year, I had skin tests and blood tests. When both came back negative, the doctor's office then scheduled food challenges for different days.
I feel no fear now eating bread anywhere, but I have trepidation with shrimp. I'll eat it when I'm in Minnesota but won't eat it traveling.
And I don't want to cook it at home because it seems gross to me and also DS is allergic to shrimp.
Just testing negative, I would not start ingesting. I think an in office food challenge is important.
I fixed some typos above.
Most of the tree nuts have component testing also, not all yet, at least when DS had his last one done. I personally think it's a good thing since they have been able to predict a person's allergic response based on which proteins they are allergic to for peanuts and tree nuts.
Here's a story in favor for the blood test...DD did not react to the venom that was injected under her skin for bees except for one spot got a little tingly/itchy, but no redness. So the allergist really thought DD's response, which was mild but could absolutely been an allergic reaction, was to the pain of the sting, but ordered the blood test anyway to be sure. She called us and said she was surprised but yes in fact DD was allergic to yellow jackets and wasps and needed to carry an epi.
Thanks for input.
DD1 had skin tests done once as a child, and since then the allergists have done blood tests on her for peanut and latex. They don't want to do a peanut skin test because that could be dangerous, and the blood test gives them a good level (which is HIGH).
Quote from: Mezzo on March 22, 2025, 03:22:10 PMDD1 had skin tests done once as a child, and since then the allergists have done blood tests on her for peanut and latex. They don't want to do a peanut skin test because that could be dangerous, and the blood test gives them a good level (which is HIGH).
Do you mean dangerous because it's equivalent to eating peanut?
Not equivalent exactly but it's still putting it in her skin when she's extremely allergic and reactive to it.
We have done both over the years to see trends. DS2 has a tendency to not be reactive during SPT - we think half life of antihistamines and other issues have made it so even the histamine doesn't react. His peanut is always tiny and left me questioning if he was even allergic as he had never reacted. But the component test showed likelihood of gut anaphylaxis which made bathroom issues make sense. I suspect his fish rxn's are similar as he always has increased bathroom activity during Lent while eating out. (We have changed protocols for eating out but it took us far too long to realize he was reacting and not the start of a stomach virus which at one one point was far too common in our household).
DS1 has always had off the charts total RAST and tests at a Class 5 or 6 for wheat, rye and barley. Egg for the longest time was a low Class 3/high 2. We challenged once at age 6 but failed, finally outgrew at 19. Via SPT and RAST he tests positive for almost everything (previous allergist was on a fishing expedition thinking he was skinny and short statured because he was eating his allergens instead of recognizing the he comes from a family of tiny folks. Current allergist was able to work through data and had us challenge peanuts and tree nuts and write off his other "positives" to corn, rice, oats, dairy and soy as negatives because he was eating with no issue.
On flip side DS2 has low total RAST, low scores for fish, peanuts and tree nuts but the panel test for peanuts showed high chance of gut anaphylaxis.
Typically, I see and read that if there's a history of reaction, that is as valid, if not more so, than skin or blood testing. Our allergist said it to me. Like with Mezzo's dd, he had no reason to risk skin testing dd, which is an exposure, because she very clearly reacted to peanut. If she were to test negative to a previous allergen, the next step would be a challenge. Dd is now 25, and has not persued testing for potential outgrowth and challenges. It's possible she's not allergic to almonds.
Had follow up appointment after cat allergy blood test.
I got skin tests done for peanuts, legume, sesame, and various nuts. Everything was negative.
Doctor said he would like me to get blood tests for peanut and sesame. If they are negative he wants to do food challenges. So. That's where we are now.
I told him that years ago I saw an allergist and wanted to do a food challenge. She refused and asked me if I knew how much they cost. I replied that I live in Canada...so NO I don't. He asked how many years I've been carrying around an epipen, and how much has that cost.
I do like this guy. I also like his nurse and his receptionist.
During our conversation, I don't remember what I said, but he responded that I had a very good understanding of allergies and tests. I told him I'm a part of an on-line group for adults and parents dealing with allergies. BUT, we don't pretend to be doctors. We tell people to go to a doctor. We help them to figure out how to avoid the allergen after they are diagnosed.
He said, "you wouldn't believe some of the online groups I've see". I said I would...I've seen that kind too, but we're not that. Lol
My anxiety is through the roof, and I think this is why. I have decided I do want the challenges, but I am terrified.
My follow up appointment is a phone call late next month. I hope we can book challenges quickly
I got an email from the allergist's nurse. It's about the food challenges. I have to supply the food.
For the peanut challenge, I'm going to pick up a small bag of peanuts. Already out of the shells, so I don't react to the dust.
What do I get for the sesame challenge?
I wonder if there is safe tahini that isn't contaminated with anything else? Did the nurse have any suggestions?
No. However, someone in a Canadian FB group sent links to a few brands.
Food Challenge booked for August. They provide the sample, I provide bread or crackers that I know to be safe, to spread it on.
Got through the call and felt immense relief. Followed by feeling sick. Nervous stomach sick.
I opted to do sesame challenge first because passing it will make the biggest improvement in my life.
Ooooh SL - I have high hopes that all goes well and you get a PASS!
Nurse sent me an email today.
They will supply chocolate tahini. I need to bring safe-for-me bread or crackers to spread it on.
Instructions say to have a light breakfast, even if I don't normally eat one. Wear loose clothing, as nurse will check for possible signs of reaction.
Bring a change of clothes in case of vomiting.
Also says she will try to call me next week in case I have questions. I replied, asking if we can book peanut challenge for near end of August, rather than waiting until after first challenge which will mean October-November. I need this anxiety to end. :-/
I already checked how much room I would have. Three hours is two much to read or play on my phone. I'm bringing a stocking to work on.
Both challenges are booked in August.
SL passing those would be life changing for sure!
Very exciting (and yes, nerve wracking too!)
Fingers and toes will be crossed for you!
Had a call from the allergist's nurse today. I really like her, she's easy to talk to. She does all the testing and most of the communication with patients.
One of the things I really like, is when I spoke with her about being so anxious about the tests, she did NOT say, don't worry, you won't react, or don't worry, you won't have an anaphylactic reaction. Instead, she said I would be in the best possible place in case I do have a reaction.
:grouphug: Truth in her words!
I got another call from the nurse today. Apparently the doctor wants me doing the peanut challenge first. She doesn't know why.
My only guess is, since my reactions to sesame have been worse, he wants to start with the lesser evil first?
Sounds like a reasonable assumption.
Sending big hugs, SL. Food challenges are scary, for sure! You are going to eat something you have been told to avoid for so long because it could be life threatening. Anxiety is to be expected! I am happy your allergist office is treating you well, that makes a HUGE difference.
I have done many food challenges. Bringing a good distraction helps. I wear comfy clothes, bring my teddy bear, a movie, a book, some music, a water bottle, and a toothbrush and toothpaste for when it ends.
The last one I learnt after vomiting so I didn't feel so gross when going home.
I also bring a safe treat for after. A little reward for making it through.
I hope your challenges are a pass! If not, know that you learnt a lot. I find it comforting in the long run to have very clear answers.
Hugs again! Keep us updated.
I plan to bring my iPad and a charger. (They have free wifi and I'll have a place to plug in if needed.) That has my book, my music, and a few apps to watch shows/movies. I'm also bringing a cross stitch project that is near completed. I just need to do outline, so just a few colours, and less concentration required. Also water for me, and crackers for the test.
They did recommend a change of clothes in case of vomiting. Tooth brush and tooth paste sounds like a good addition.
I plan to wear one of my skirts and an oversized t-shirt. Since some reactions have previous started on the back of my legs, I want it to be easy to show without stripping. Also, I just find shorts to restrictive and sweaty.
Nurse also suggested a sweater or something as many people find the AC to cold. I'm unlikely to feel cold, but will pack something just in case.
Update.
I did the peanut challenge first. Nurse took me into a room. Took BP (extremely high) and pulse ox (98). Looked in my mouth, and checked skin for any marks. Then brought me first bit of pb on a cracker. After second serving, I felt like my leg was itching, but tried to not scratch it as that would make it look worse. When the nurse came back I told her and we both agreed, it was just dry skin. Test continued with no further issues. An hour after last serving, the doctor came in. He said I was NOT to eat any peanut or even May contains for 24 hours. Any rash or hives, I was to take a picture for him.
Before eating each serving she check my pulse ox. It was always 96 or higher. BP was only taken at the beginning and end. Both times it was very high at the beginning, and higher at the end. lol
Almost a month later I did the sesame challenge. Since my reactions to sesame were much worse, I guess I was a lot more anxious. They provided a chocolate tahini for the test. After the first serving I suddenly felt my mouth itching and the back of my tongue swelling. I took a few drinks of cold water, closed my eyes and did some deep breathing. The fact that I could take a deep breath was encouraging. I started watching a show on my phone (forgot my iPad) and started sewing. After a few minutes I realized the "reaction" had stopped. When the nurse returned with the next serving I told her, and that I thought it was just anxiety. She agreed, and we continued with the test. No more issues in the office. However, about 7 hours after getting home, one arm was itching, and maybe a bit rashy. Since it wasn't spreading, I waited. It went away, before I went to bed. More anxiety.
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I'm posting about this because anyone suddenly eating something that previously was deadly to them, is going to be anxious. You know your own body better than anyone else, so if you think it's anxiety and the medical professional also things it's anxiety, consider continuing the test.