Hi Daz -- I saw this a couple of days ago and thought, "This is right up my alley", but didn't answer because I wasn't sure I completely understood your question.
I'll give it a try now :)
The first part:
Which made me think, even if your
tested ferritin level comes back as a
good number, could it still be
possible that it is actually at a
‘good’ level due to it being raised by
inflammation...and without the
inflammation the real ferritin level
would be below optimal (inflammation
may be raising tested ferritin levels,
from sub-optimal to optimal).
The answer to this question is: it absolutely can. This case report describes an 83 year-old man who had restless legs syndrome that was unresponsive to drug therapy. He had a history of heart disease, slightly elevated erythrocyte sedimentation rate, and a ferritin level of 93 µg/L. There was no anemia:
Blood tests were essentially normal. In
particular, hemoglobin was 12.7 g%, mean corpuscular
volume was 89, transferrin saturation was 25% and serum
ferritin was 93 µg/L. ESR was slightly elevated at 52.
He was treated with oral iron, ferrous fumarate equivalent to 90 mg of oral iron per day. After 4 months, the ferritin level was 136 µg/L. (By this point his RLS had almost totally resolved.)
The interesting thing about this case report is the astounding finding that a bone marrow biopsy tested negative for iron, despite a ferritin level of 93 µg/L and a blood count which would not qualify as anemia!
Where to set the point at which an elevated ferritin level rules out an iron deficiency is an open question. I know of no published evidence that establishes a relationship between other markers of inflammation and ferritin levels, so this is one area where a great deal of care and attention is needed to avoid missing what may indeed be an iron deficiency.
The British Columbia Ministry of Health's clinical practice guidelines remind physicians that the ferritin level is a factor in determining the probability of iron deficiency:
Serum ferritin levels and iron status:
less than 15 → diagnostic of iron deficiency
15 - 50 → probable iron deficiency
50 - 100 → possible iron deficiency
more than 100 → iron deficiency unlikely
persistently more than 1000 → consider test for iron overload
less than 12 → diagnostic of iron deficiency
Of note, the guidelines also say:
may be unreliable in patients with
chronic disease or malignancy
non-hematologic symptoms can occur
when the serum ferritin is in the low
normal range (less than 50 ug/L)
higher levels of serum ferritin do
not exclude iron deficiency
persistently elevated serum ferritin
levels (greater than 1000 ug/L), but
without chronic inflammatory disorder
→ recommend testing for iron overload
(refer to Iron Overload -
Investigation and Management)
The second last one is what gets people into trouble.
You asked about my labs. Here they are:
Test 1: December 14, 2010:
RBC 4.2 * 10^6 /µL [L!]
hemoglobin 129 µg/L [L!]
haematocrit 38% [L!]
platelets 222 * 10^3 /µL [L!]
MCH 30 pg
MCHC 34 g/dL
MCV 89 fl
This is mild anemia. No intervention recommended. Gamma globulins were elevated on this test, so the doctor suspected an infection as the cause of the anemia.
Test 2: January 4, 2011
RBC 4.7 * 10^6 /µL
hemoglobin 14.2 µg/L
platelets 214 * 10^3 /µL
MCH 30 pg
MCHC 34 g/dL
MCV 89 fl
ferritin 95,7 µg/L
Suddenly, the anemia is gone. The ferritin has been tested and is normal. Note that at this point, all I have done since the last appointment is take some B-vitamins. I was not eating a paleo diet yet. By now, the doc has ruled out an iron deficiency as the cause of my troubles.
Test 3: June 3, 2011
This was done by the endocrinologist. By this point I have seen not one but four specialists. I am getting sick of doctors.
RBC 4.6 * 10^6 /µL
hemoglobin 139 µg/L
platelets 199 * 10^3
MCH 31 pg
MCHC 36 g/dL
MCV 86 fl
ferritin 99.3 µg/L
Test 4: June 6, 2011
Three days later, I am back at my primary physician. For some reason, he orders a serum iron alone, and thinks to check CRP:
RBC 4.6 * 10^6 /µL
hemoglobin 139 g/L
platelets 240 * 10^3
MCH 31 pg
MCHC 35 g/dL
MCV 87 fl
serum iron 188 g/L [H!]
CRP (standard) <0.8 mg/L
The MCV on the last two tests has been lower. The serum iron is high; it has a circadian rhythm and can vary enormously, but as this is a single measurement and not alarmingly high, and since everything else looks okay, the doc doesn't think it is of interest.
Test 5: August 2011
I saw a second endocrinologist in August. (Unfortunately, I do not have a copy of the labs. I am due for a follow up this coming September, and I'll ask for one.)
On reviewing the labs with me, he said I appeared mildly anemic, asked about my dietary habits and recommended I make an effort to get more iron in my diet (I presume he measured ferritin and did a blood count; he wrote me a letter that covered only the endocrinological aspects of the test results).
Test 6: December 12, 2011
RBC 4.5 * 10^6 /µL
hemoglobin 136 g/L [L!]
platelets 206 * 10^3 /µL
MCH 30 pg
MCHC 33 g/dL
MCV 91 fl
Vitamin D is checked at this visit because I was complaining of joint pain and had been deficient in the past. It is 21 ng/mL (52 nmol/L), so I go back on supplementation.
Test 7: February 19, 2012
I am back in my old hometown and go to see my previous doctor. He has seen me every year or so the past few years. Some things have gotten better over the last 18 months, other things worse. To rule out inflammatory disease he orders a range of tests.
I have been paleo for about two months at this point, but I still don't feel right. My sleep -- never good to begin with -- is getting worse, and I'm depressed. All my muscles are sore and tense. I can't concentrate, which makes work difficult.
total cholesterol 5.52 mmol/L [H!]
triglycerides 0.49 mmol/L [L!]
HDL cholesterol 2.26 mmol/L
total:hdl ratio 2.4
LDL, calculated 3.04 mmol/L
His words: "This looks fine. You have lots of the good stuff, so I see no reason to be concerned about your cholesterol."
erythrocyte sedimentation rate 7 mm/h
CRP (sensitive) 0.1 mg/L
The blood count:
RBC 4.3 * 10^6 /µL [L!]
hemoglobin 132 g/L [L!]
haematocrit 39% [L!]
platelets 208 * 10^3 /µL
MCH 30.6 pg
MCHC 33.8 g/dL
MCV 92 fl
The "anemia light" is back, and...
ferritin 11 µg/L [L!]
to which I can only say, what the hell happened here?
The doctor prescribes iron replacement. Minimum duration 3 months, with a follow-up recommended at 4 weeks. I started taking 70 mg of elemental iron per day, in the form of ferrous gluconate.
Test 8: April 13, 2012
After five weeks of iron replacement, now back with the doctor who ordered the first three tests:
RBC 4.8 * 10^6 /µL (Never in all my years has the RBC been this high.)
hemoglobin 142 g/L
haematocrit 45% (Ditto for hematocrit.)
platelets 253 * 10^3 /µL (Ditto.)
MCH 29 pg (My poor bone marrow has never been so happy in its entire existence. Finally getting enough iron, it's churning out red blood cells so fast the MCH is actually dropping.)
MCHC 33.8 g/dL
MCV 93 fl
serum iron 124 µg/L
ferritin 35.9 µg/L [L!]
transferrin 296 µg/L [H!]
transferrin saturation 29.7% (I had taken an iron tablet about 90 minutes before testing.)
The total iron binding capacity is high. Even though ferritin has gone up 25 µg/L, it's clear that the system is still iron-hungry. (This throws a new light on Test 4 from the previous June, after I had started running regularly; without a TIBC result, I can only speculate, but my hunch is that the serum iron was elevated because my TIBC was going up. More transferrin means increased absorption from diet.)
Upon seeing this result, the doc says he wants me on iron for at least three more months, with follow-up testing at that time. That's scheduled for the end of July.
The hematological response to the iron replacement is apparent and this response is considered (quite apart from the low ferritin on the previous test) diagnostic of iron deficiency.
This is despite the fact that I had anemia sometimes, and sometimes not, and always very mild. The hemoglobin was nearly always normal. Ferritin was normal as late as June 2011, and all the while -- already in 2010 -- I had the same symptoms which are now going away on iron replacement.
So: In a person with symptoms, these tests are simply inadequate.
I honestly can't say whether the ferritin at 95 µg/L was an accurate reflection of my iron stores. The other inflammatory markers were unremarkable, but I suspect that something was going on. It may have been as simple as light inflammation caused by lots of physical activity. I am very physically active. I'm convinced that an active person "consumes" iron in ways a sedentary person does not (one does refer to "runners anemia" in the medical literature.)
But apart from all the labs, which are really just tools, I feel the best I have in years. All the things I mentioned in this answer still hold true, only even more so a month later.
And that's what counts.