Why is there a difference between hemoglobin levels in men and women?

[neva525]

That is, why do men have higher hemoglobin levels in comparison to women? What could be the reason for that? It's really important, thank you.

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[Dires]

Is this a ****ing joke?

 

[neva525]

I wish it was. I have my answer but supposedly it's not a correct one.

 

[ChrisMack390]

Iron is sexist

 

[Psai]

Men are larger and this means they have larger bones which have more blood cell producing bone marrow. Also male kidneys have a greater diameter so they produce more epo causing increased red blood cell production. I just made all of that up.

 

[.hematoma.]

I thought it's because of menstrual bleeding. I remember my professor saying that we accept a lower level in women due to menstrual bleeding. But I can also see how @Psai makes sense as well

 

[Terry Toma]

Our magnetic personalities prevent the loss of iron.

 

[WheezyBaby]

Iirc, it's predominantly menstruation related, but I think testosterone also stimulates epo

 

[jd989898]

We don't really know why. I would suggest reading this paper if you're interested.

The sex difference in haemoglobin levels in adults — Mechanisms, causes, and consequences

The leading hypothesis at this point is that the different selective pressures on males and females led to different optimal hemoglobin concentrations. For example, higher hemoglobin will increase one's physical performance, but also increases the risk for thrombosis. Perhaps males, who have historically fought/hunted more than females, benefitted from this risk. We know that the difference is not due to menstruation or differences in EPO. Even in mammalian species which do not menstruate, the male organisms maintain higher Hg concentrations than do the females. Also, men have the same EPO levels as women.

 

[TooMuchResearch]

It's not menstrual bleeding unless the difference only exists between males and females in their menstruative years.

 

[ChrisMack390]

It's not menstrual bleeding unless the difference only exists between males and females in their menstruative years.

Also, less blood volume shouldn't affect the [] of heme in the blood.

 

[mimelim]

Also, less blood volume shouldn't affect the [] of heme in the blood.

Yes it does. Not hyperacutely, but blood loss absolutely drops a patient's crit or Hgb.

 

[sazerac]

Epo levels are the same in men and women. The answer isn't related to bone marrow, and menstrual women genuinely have a lower set point (and aren't trying to catch up to men). The "how" is most likely at the level of sex differences at the JGA.

As for the OP's question of "why", that is peering into the mind of God. Evolutionarily it gave some hazy advantage to proto-mammals of reproductive age.

"Because menstration => blood loss" is a handy memory device for Goljan-level understanding of physiology, but the real answer (if it is ever found) is going to be more than one sentence long. The more one studies sex differences at the biological level, it is more remarkable that so many other parameters are the same between the sexes.

 

[Raryn]

Testosterone is probably a big part of it. It has epogenic effects in and of itself. Hence why you have to monitor thr hematocrit for everyone on it.

 

[ChrisMack390]

Yes it does. Not hyperacutely, but blood loss absolutely drops a patient's crit or Hgb.

Hm. Any idea how that happens? Are RBCs lost at a faster rate than the rest of blood?

 

[Raryn]

Hm. Any idea how that happens? Are RBCs lost at a faster rate than the rest of blood?

The body maintains circulating volume, and plasma expands at a much faster rate than RBCs. You can regenerate most of your plasma volume with a couple day's worth of eating, drinking, and normal liver activity. RBCs will take a much longer time (4-8 weeks). Hence why you can't donate whole blood that often but if you donate just plasma, the time limit is a lot shorter.

 

[pacman2018]

That is, why do men have higher hemoglobin levels in comparison to women? What could be the reason for that? It's really important, thank you.

What do you think they were marching about the other day...? Jeez

 

[CaliforniaDreamer]

Hm. Any idea how that happens? Are RBCs lost at a faster rate than the rest of blood?

No but the fluid component of the blood is replaced faster. Immediately after loss of some blood volume you wouldn't see a change, but it would start to drop soon after that time point.

 

[Psai]

Hm. Any idea how that happens? Are RBCs lost at a faster rate than the rest of blood?

Fluid shifts man. You need volume to maintain pressure. There's the interstitial, intracellular and intravascular. Intravascular fluid is only a small fraction of total body fluid. I'm sure they went over this in physiology.

 

[BurghStudent]

#triggered

 

[Merely]

Is this a ****ing joke?

I don't understand, what are you shocked about?

 

[deleted564680]

#HgEquality

 

[neva525]

Thank you for your help, guys.

 

[SurfingDoctor]

Y is the 25th letter, X is the 24th letter. So...

X + Y= 24 + 25 = 49
X + X = 24 + 24 = 48

49 is higher than 48... and that is how hemoglobin is made.

Hm. Any idea how that happens? Are RBCs lost at a faster rate than the rest of blood?

Also, RBCs make up about 45% of blood volume, while leukocytes and platelets make up ~1% of blood volume. Thus in blood loss, even if a % of whole blood is lost, the absolute value decrease in RBCs is greater than absolute values of other circulating blood cells. That's why Hgb drops are more reflected in acute blood loss than other cells.

 

[FourniersGreenGang]

You're all wrong, it's because of the patriarchy!

 

[mw18]

Testosterone treatments for hypogonadism can lead to polycythemia, so it seems like there could be a correlation there. But it seems like it would be fairly simple to test with testosterone measurements (not a great test, but if you did 8 am measurements or 8 am and midnight measurements to get an idea) and Hgb/hematocrit in males and females. I'm sure it's more complicated than that.

 

[Perfect Hair Day]

That is, why do men have higher hemoglobin levels in comparison to women? What could be the reason for that? It's really important, thank you.

The Y chromosome persists for a longer time in the nucleus of the red blood cell, conferring a longer half-life; for women, the RBC nuclei contain a single X chromosome, which is not as hardy as the Y chromosome; as the RBCs die off sooner in women than they do in men, the marrow must regenerate the RBCs at a faster rate - but since women have less bone mass than men, the response is fall's a little short of the 13.5 mark that is considered the cut-off for anemia in men. This is not pathologic so we call it 12.5 as a cut-off in women.

Good luck with your essay-response homework. I hope this helps 🙂

 

[Psai]

The Y chromosome persists for a longer time in the nucleus of the red blood cell, conferring a longer half-life; for women, the RBC nuclei contain a single X chromosome, which is not as hardy as the Y chromosome; as the RBCs die off sooner in women than they do in men, the marrow must regenerate the RBCs at a faster rate - but since women have less bone mass than men, the response is fall's a little short of the 13.5 mark that is considered the cut-off for anemia in men. This is not pathologic so we call it 12.5 as a cut-off in women.

Good luck with your essay-response homework. I hope this helps 🙂

If your rbcs have nuclei u got a problem

 

[Perfect Hair Day]

If your rbcs have nuclei u got a problem

If OP believes it, that's be fantastic.


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[.hematoma.]

Hate to bring up an old thread, but I just did a Uworld question and in the explanation they mentioned that men have higher hematocrits because of testosterone (increases RBC production). So if you get it on a test, it's because of testosterone!

 

[doctorbob23]

Im guessing men have increased muscle mass overall therefore they have a need for a greater oxygen carrying capacity manifested by higher heme

 

[gracie369]

Because how much hemoglobin do you really need to go shoe shopping!?

 

[cellsaver]

.

 

[bugsterizer83]

I could not resist

sorry

 

[Psai]

I could not resist

sorry

mind
blown