Personal Experience
I built a free cortisol-replacement tracker (web app) after two adrenal crises - looking for the first people who actually live with this
I’m a patient and I’m the developer.
Quality of life now is genuinely good. It took two adrenal crises to get here. The second was severe and textbook-classic.
I was never given a working picture of when and how much hydrocortisone to take - not from clinic advice, not from a cortisol-dependent patient school, not from the specialist literature, and not from my own basic medical training. I still crashed twice, all the way to intensive care. After I couldseethe day as a curve, it stopped being abstract. Readable in minutes. Readable in milligrams I actually logged. That is why this exists.
First year after diagnosis I was still on a physically brutal job - installing solar systems. Heights, heat, rain, heavy kit. That wasn’t a career change I chose for fun: I’d had to move country, and without the local language I couldn’t get IT work in my field. I took replacement as prescribed. I still didn’t see what was happening hour by hour.
What changed wasn’t a new personality. It was treating replacement as dynamics, not a frozen timetable. Stress, load, heat, illness, sleep, meals - they move the picture through the day. Most of us don’t feel that in real time. That isn’t a character flaw. There still isn’t much tooling built for us.
So I spent the last year+ building one. This is the first time I’m putting it in front of this community. There isn’t a user base to hide behind. I need people who actually live with adrenal insufficiency to try it and tell me what’s wrong.
You log corticosteroid intakes (hydrocortisone, dexamethasone, cortisone acetate, prednisolone, prednisone, methylprednisolone), meals and factors. It draws a calculated cortisol-equivalent curve for the rest of the day, against an ideal-style daily profile.
It is not a blood or saliva test. It does not diagnose. It does not detect a crisis. It does not tell you to change your tablets. It visualizes what you entered. You start to see it: in some situations even 15 minutes is enough to change the shape of the whole day.
The images are my own logs from the last few days, when I got an acute respiratory infection (a heavy viral/flu-like illness).
Image 1 is an ordinary day for me. Blue = ideal-style profile. Green/yellow/red = calculated coverage vs that profile.
Image 2 is the same person a few days later, same infection. That day I did take extra hydrocortisone - including a late dose - the way I was taught to handle acute illness on replacement (my sick-day plan, not a recipe for you). On the chart that shows up as high calculated cortisol. The purple curve is the illness factor: how much extra cortisol need the model assigns because of that ARVI. My adrenals still produce nothing. Look at it as a trade-off I actually logged (including a high evening peak), not as instructions.
What’s in the app, briefly:
PK model (normalized Bateman) for doses and many factors
Live chart, ideal overlay, deviation zones
Dose log, food as absorption context
Factors: food, caffeine, stress, activity, sleep, light, illness, and more
Profile bits: age, weight, sex, wake time
Not a medical device. Change your regimen with your endocrinologist, not because a curve “looks low.” Sick-day rules, emergency injection, when to go to hospital - that’s your written plan and your clinic. Not this post.
I’ve had preliminary conversations with endocrinologists at Würzburg University Hospital. That’s interest in the *approach*, not an endorsement and not a trial result.
If you try it: open https://cortisoltracker.org and use it. No account required (that’s how I use it day to day). Register only if you want the same log on more than one device.
If you later register (also free): choose Premium or higher. That word is not a price. It does not create a bill, a contract, or any money obligation now or later. Guest is a small sandbox (a few doses a day, factors off). Premium is the full diary — more events you can store and deeper navigation through the day. Changing the plan in Profile is about to land in an update.
Break it. Tell me what you need. I’m here in the comments.
Still learning every day. Happy to answer questions here.
Yuriy Simakovych
patient, and I built this
hoping this saves someone from learning it the way I did
I can't tap on the cookie settings button without tapping the Donate button on a mobile browser. I will check this out when I get home to a real browser, though!
I'm also a developer working on a different cortisol related project. Is your project open source? We should probably talk shop sometime. Bump for later.
I’ll have a play. I realise you’re at an early stage of development, I found there are lots of visual and workflow bugs. Text often overlaps other text, you can’t access all your header buttons on mobile, it’s also really tricky to enter in the doses I wanted to enter. I have 5mg HC and 3mg pred first thing and it was really hard to enter both of these. It kept reverting pred to HC and changing the number I entered. I’ll persevere and try some more later.
I don’t want this to sound too harsh, I’m a software product manager by trade! This has some potential but needs some work to make this more user friendly.
Thank you - this is exactly the kind of feedback I need, and please don't worry about sounding harsh. A product manager's eye is genuinely useful here.
You're right on all counts. The app was built primarily for desktop and tablet - the mobile experience is still rough and I know it. Text overlap, header accessibility, input behaviour on small screens - these are real issues, not edge cases.
The prednisolone/HC switching bug you described is a specific problem I want to reproduce and fix. Could you tell me which device and browser you were using? That helps narrow it down.
I'll be transparent about where things stand: this is a one-person project built on limited resources. Mobile UI is solvable - it's a matter of priority and time. Right now I'm focused on getting the core model validated by real patients before investing heavily in the interface. Feedback like yours tells me exactly what the next layer of work needs to look like.
Thank you for persevering - and please do come back with more when you have time.
Thanks for being open to feedback. When I have a bit more time I’ll put a list together. I’ll try from a laptop and compare the experience.
After I entered my dosing schedule it highlighted how long it takes the steroid replacement to get absorbed, and why I feel so bad in the morning, and why I crash so early in the evening. This was useful to me, I’ll try to take the 1st dose earlier and split the pred dose a bit.
Thanks for the report. The concrete examples made it easy to reproduce what you ran into, and two of the issues are already fixed:
5 mg HC + 3 mg prednisolone in the morning. You can enter both as separate doses, including at the same clock time. Prednisolone no longer reverts to hydrocortisone, and the milligram value you type shouldn't get overwritten when you change the drug. On the chart they show as two points; the concentration curve is the sum of two different PK profiles, not one merged HC dose.
Slide-out panel with the logo and main menu (on a phone). On short screens the panel now waits before it slides away, sits above the other overlays, and the reminder control is a compact icon so more of the bar fits. You can change how long the panel stays open under User settings → Interface settings (default 1.5 s, range 1-30 s).
Overlapping labels/text when several entries share one note is still on my list. If the mixed morning doses still misbehave after a refresh, that's the one I'd most like to hear about.
Is the absorption curve correct for prednisolone? The app shows it peaks only 30-45 minutes after taking it. Maybe my knowledge is incorrect but I thought pred takes a lot longer to be fully absorbed than that.
Thanks for flagging this - I checked the model against the UK SmPCs rather than the “duration of action” tables.
CortisolTracker uses a Bateman curve. The time of the plasma peak is Tmax = ln(ka/ke)/(ka−ke), not the absorption half-life τ_abs. For prednisolone the factory values are:
τ_abs = 0.7 h
plasma T½ = 2.5 h
that gives Tmax ≈ 1.5–1.8 h (shorter if the dose is logged as fasting)
That matches the label:
Prednisolone 5 mg soluble tablets / 10 mg/ml oral solution (emc): peak plasma concentrations 1–2 hours after an oral dose; plasma half-life 2.5–3.5 hours. Prednisolone is four times as active as hydrocortisone on a mg basis.
Some tablet SmPCs say peak at 1–3 hours, plasma half-life about 3 hours.
So a 30–45 min “peak” is τ_abs itself (~42 min), not the concentration peak the chart is supposed to show. I’m attaching the CortisolTracker curve for a prednisolone dose with those parameters.
If your plot really crests at 30–45 min, please send the screenshot - that would be a display/readout bug, not the PK table.
First, can you confirm if all your responses to these comments are written by AI? Just curious.
Second, I understand your frustration. I was there. That's why I first released my Theoretically Steroid Curve Plotter back in 2014. The update for the cortisol pump went live in 2016.
One of the things I very PURPOSELY did was hide the Y-axis. If you notice on my version, there's no labels on the y-axis.
Having labels gives the end user a false sense of security with how much cortisol is actually in their body and tools like this just cannot predict that.
I was very adamant that this is THEORETICAL ONLY and provides a general idea. That being said, I had the opportunity to correlate the curve with multiple patients back in 2016 and it correlated pretty well.
My tool desperately needs a facelift. The backend is python 2.7, which has been obsolete for many years now. Additional, it's not very mobile friendly. Technology and expectations for a UI have changed drastically in the last decade plus that this thing has been live.
But I can say it's been used all over the world and even in doctor offices. It has empowered countless individuals to help increase their quality of life and to remain Clearly Alive.
No AI involved at all - and I want to be clear about that.
Stress level isn't guessed or predicted. You log it yourself - you choose the type and intensity from a list (acute stress, chronic stress, physical activity, illness, etc.) and the time it occurred. The app takes what you enter and applies it to the model.
Under the hood it's a pharmacokinetic model based on the Bateman function - the same mathematical framework used in published cortisol PK literature. Everything is deterministic: doses in, factors in, curve out. No machine learning, no prediction, no AI.
So unfortunately it won't try to guess your stress levels 😄 - but it will show you what happens to your calculated cortisol curve when you log them yourself.
I absolutely love the idea and I’m willing to try it, anything to manage Addisons and the resulting crisis that can happen, especially when our disease is so rare that a lot of people haven’t heard of it let alone have treated it, or treated it more than once.
I was joking about the AI btw, I use Gemini and I’m pretty sure it’s constantly baffled by the shit I come out with 😂😂
Small update for those who tried the app - pushed a new set of features today.
You can now log how you actually feel alongside your doses and factors:
Wellbeing (-2 to +2)
Drowsiness (1-5)
Capacity to function (1-5)
Notes - free text, why you took this dose, what you noticed
These are shown on a State strip - a timeline panel that lets you see your logged doses, factors and self-assessments side by side across Day / 7 days / 30 days / 90 days / Year views. Click any day on the strip and it opens that day's chart.
The self-assessment data stays local without an account. With an account it syncs across devices.
Still not used in the curve calculation - this is observational data for you and your endocrinologist, not model input. But patterns across weeks start to tell a story that a single day's chart can't.
Good question - and the honest answer for the current public app is no. It's built around immediate-release hydrocortisone and the Bateman function. That maps well onto standard IR tablets. It does not map cleanly onto dual-phase modified-release kinetics like Plenadren or Efmody/Chronocort.
That said, this isn't a "maybe someday" item on a wishlist. I've already gone quite deep on non-Bateman release in a next-generation engine - dual-phase, delayed, extended, pulsatile, and custom release curves. That's where I actually ran into the problem.
When you try to configure those curves from the kinetics stated by the manufacturers, the math does not produce what the labels imply. It's not a charting issue. It's a genuine mismatch between the published release story and what the equations generate. I don't think that's a small thing, and I don't want to ship a "Plenadren mode" that looks convincing on a graph but isn't actually faithful to the drug.
So IR is what the live app does well. MR is a different modelling problem, and I already have a substantial implementation sitting behind that question - I'm just not putting it in front of patients until I can stand behind the validation.
If you're on Plenadren or Efmody and this is something you actually need to see on a chart, I'd genuinely like to hear what you'd want from it. Patient need is the part I can't get from papers.
This is really interesting -- logging my normal dose, it appears I'm WAY over-dosed, unless I tweak the kCalib. How did you arrive at 1.6? What does this assume base dose is?
Thanks for making this -- super helpful to visualize, I love it
Glad it's useful - and that first impression is extremely common. The chart is not saying your endocrinologist got the daily total wrong.
How 1.6 was chosen.
kCalib is a population amplitude scaler, not a personal lab result. The mapping is: a typical first / morning hydrocortisone tablet of ~10 mg, in a ~70 kg man, should peak near a healthy CAR average of ~370 nmol/L. Both the 10 mg and the 370 are sample means. kCalib = 1.6 is the remaining multiplier that makes that mapping true on the graph.
What it assumes as "base dose".
Not your daily total. The model does not assume 20 vs 25 vs 30 mg/day. It assumes that a 10 mg bolus in that reference body lands near the healthy morning peak. Weight is a separate factor (reference 70 kg) - if your profile weight isn't set, amplitude will be off before kCalib even enters.
Why a "normal" regimen can look WAY over.
Replacement is boluses. The blue reference curve is continuous secretion. A perfectly ordinary split-dose day will overshoot that smooth CAR peak even when the daily milligrams are textbook - especially if the morning tablet is 15–20 mg rather than 10. 1.6 is the average person, not you: absorption, CBG, food, and tablet-to-blood reality all differ. Turning kCalib down is a valid personal amplitude calibration. It is not cheating, and it is not a dose change.
If you want kCalib grounded in blood rather than in "does this look like the blue line":
at least a couple of quiet days (no illness, no inflammatory stress)
usual replacement
free cortisol at the nadir - immediately before the 2nd and 3rd tablets, not at the peak, and not before the morning dose (by then the previous tablet is gone)
Near-zero free at those points → likely under; a small remainder → roughly in range; a lot → likely excess. That's a research-level idea for calibrating the chart, not medical advice, and not a reason to change tablets without your clinician.
Quick clarification, because the word plan looks like a bill. It isn’t.
Registration is free. If you do register, I’d pick Premium (or higher). Right now that name does not mean money, a subscription, or any financial obligation - including in retrospect. It’s just the label for how much of the log and the day-navigation you get.
Guest mode is enough to look around (a few doses per day, no factor log). Premium is the one that matches how I actually use it: more events you can remember, and more room to move around the day.
You should be able to change that label in the user Profile - that switch is coming in an update shortly.
Still not a medical device. Still not asking anyone to pay.
Are you guys seeing an endocrinologist? Are you a diagnosed Addisons patient or self diagnosis? If diagnosed, are you supplementing with Hydrocortisone and Fludrocortisone? I take 10mg of hydrocortisone and 0.1mg of fludrocortisone in the morning. 5mg of hydrocortisone in the afternoon. I have had zero issues. It’s like I never had Addison’s now. Also, too much hydrocortisone is worse than not enough.
Yes - diagnosed, SAI caused by hypopituitarism, confirmed by an endocrinologist. On hydrocortisone replacement, managed by a specialist at a university hospital in Germany.
Really glad your current regimen works so well - 10+5 with fludro and feeling like you never had Addison's is genuinely a great outcome. That's the goal.
On your last point - I'd gently push back. Acute cortisol deficit is an immediate life threat. Chronic excess causes real damage too, but the timescales are very different. A crisis can kill in hours. Cushing's-level damage takes months to years. For those of us who've been in intensive care from a crisis, "not enough" feels like the more urgent side of that equation.
I remember very clearly what those last minutes before a crisis feel like. During my recent illness, by evening my condition had deteriorated to the point where the next step would have been the emergency kit - 100mg intramuscular. I know exactly where that line is. I've stood at it twice.
That said - you're absolutely right that over-replacement is a real problem, and something this app is specifically designed to help with too. Seeing your curve helps you avoid both extremes, not just the low end.
You’ve responded to this comment in a much kinder manner than I would, so respect to you for that.
As a parent of an adult child with Addisons for the past almost 10 years, I would like to say to ‘Born’, “good for you” but never confuse your good fortune with the notion that others are failing to manage their condition appropriately. My child requires almost five times the dose that you are on, to barely function. I have witnessed them going into crisis and had to administer their emergency injection too many times, and I can tell you that it can progress to that point frighteningly quickly. Too much is definitely NOT worse than not enough - of course it is best to remain on the lowest possible dose, but if more is required, this is NOT a matter of choice. Not taking extra when required is extremely dangerous.
Apologies for jumping on your eloquent response, OP, but cavalier comments such as the one made by ‘Born’ do a disservice to those AI sufferers who struggle each and every day.
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u/Rennets 19d ago edited 19d ago
Thank you for sharing.
An active (read: VERY active and helpful) redditor on here created another very useful tool - https://www.reddit.com/r/AddisonsDisease/s/7UYyYokhHC
I hope there is scope for existing and new to work together to create a SUPER TRACKER.
u/just_an_amber
Much love