Most Things Biology

14.4 Making and Recycling Red Cells

Case home  ·  Start at the beginning  ·  The Reveal

Time To Read

27–40 minutes

Date Last Modified

Blood · Chapter 4 of 7

A steady population means production equals destruction. This chapter builds both ends — red marrow and its megakaryocytes, the six-stage line from hemocytoblast to disc, the reticulocyte count, the hormone from the kidney that answers oxygen and never counts cells, the macrophage that takes a worn cell apart — then sorts the anemias and polycythemias and runs her workup, down to an EPO that should be switched off.

The question you will answer

Every part of the machinery works — marrow, spleen, iron, bilirubin — and there are too many red cells. Is the factory over-producing on its own, or is somebody sending it an order it should never have received?

Opener · Stem Cell to Disc · about 1¾ minutes

The opener is the same narrated animation you will watch in Scene 1.

Watch it in Scene 1 ↓

Watch the opener first. It sets the question; the chapter answers it.

1

Read the chart

Patient chart · Stina

2015 · age 40 · the hematologist’s erythrocytosis workup

Production
Reticulocytes 1.8% (0.5–2.0), corrected 2.0 — a marrow working a little hard, not racing. Red-cell mass by isotope dilution: 36 mL/kg (> 32 = true erythrocytosis).

Destruction
Bilirubin 0.7 mg/dL; LDH normal; haptoglobin high (acute phase, not hemolysis); spleen 13 cm, mildly enlarged, counts normal.

Supplies
Ferritin 220 (acute phase); transferrin saturation 28%; B12 540; folate 12 — all adequate. Iron tablets stopped.

The order
Erythropoietin 44 mIU/mL (4–26) — HIGH with a saturation of 98% and a pO₂ of 94. JAK2 V617F negative. Carboxyhemoglobin 1%. No sleep apnoea. Hemoglobin electrophoresis HbA only.

Marrow
Posterior iliac crest biopsy: normocellular for age, mild erythroid expansion, megakaryocytes normal, plasma cells 6% (MGUS criteria met: < 10%).

Told
“Secondary erythrocytosis, cause unclear. Phlebotomy if the hematocrit passes 52. Recheck the EPO in a year.”

Chart clues this module: 1–3 · earlier chapters · 4 · this chapter

Before you go on · your prediction

Reticulocytes a little up, destruction normal, supplies adequate, JAK2 negative, oxygen normal, EPO high. The extra red cells come from…

Open the one you lean toward. Nothing is recorded and nothing is revealed — you come back to it at the end.

A marrow that has gone its own way — a myeloproliferative disease like polycythemia vera

Ask what polycythemia vera does to the EPO level (the loop sees too many cells and switches the hormone off) and what JAK2 is. Then look at her EPO and her JAK2.

Tissues that are starving despite a normal saturation — a hemoglobin that will not let go

Ask what the electrophoresis showed, and what a high-affinity variant does to the curve; then whether a normal HbA can starve a tissue at 94 mmHg.

An honest marrow obeying an EPO that is being made somewhere it should not be

Ask where EPO is made, what switches it on, what should switch it off at 98% saturation — and what else in the body can make it when the kidney has no reason to.

From Stina’s diary

2015 · age 40 · “Undetermined significance”

2

The story

Three short movements: the case, the anatomy and physiology, then the tie back to Stina. Each links to the scene where you’ll see it move.

I · The factory: red marrow, six stages, fifteen days

Hematopoiesis happens in red marrow — in adults the flat bones and the proximal femur and humerus. On a marrow section the framework is reticular fibres; between wide thin-walled sinusoids lie the hematopoietic cords, and the cell that proves you are in marrow is the megakaryocyte, 50 to 100 micrometres with a multilobed nucleus. Every formed element descends from the hemocytoblast, the hematopoietic stem cell; lymphoid hematopoiesis gives the lymphocytes, myeloid hematopoiesis everything else. For red cells the notes draw six stages. The proerythroblast — a colony-forming unit — has acquired receptors for erythropoietin: that is what commitment means. The erythroblast builds ribosomes and gathers iron. The normoblast fills with hemoglobin and ejects its nucleus. The reticulocyte, still carrying ribosomal RNA that stains as a blue net, enters the blood and finishes in a day or two (the lecture’s two weeks is a slip); one to two percent of red cells, and counting them reads the factory’s speed. Fifteen days; two million cells a second. Supplies: iron, bound by gastroferritin in the stomach, carried on transferrin, stored as ferritin; B12 and folate for DNA — Maude’s intrinsic factor.

See it move: Scene 1 · Stem Cell to Disc · Scene 2 · Counting the Factory’s Speed

II · The order: a hormone that answers oxygen and never counts cells

Erythropoietin is a glycoprotein made by interstitial fibroblasts in the kidney (the lecture’s “granular cells” is a slip). When the oxygen reaching the kidney falls — fewer red cells, thinner air, a smoker’s carbon monoxide — an oxygen-sensing enzyme stops degrading hypoxia-inducible factor, HIF accumulates, and the EPO gene switches on; production climbs up to tenfold. The notes’ starred line: the loop is controlled not by the number of red cells but by whether oxygen is arriving — “can they do their job?” — why renal-failure patients run at half a count and why recombinant EPO is blood doping. More cells, more oxygen, HIF degraded, EPO off. At the other end, after about 120 days, macrophages in spleen, liver and marrow take the cell apart. Globin becomes amino acids. Iron goes back on transferrin or into ferritin. Heme becomes the bile pigments — biliverdin, green, then bilirubin, yellow — carried on albumin to the liver, conjugated, secreted in bile, turned by gut bacteria into stercobilin and urobilin — brown feces, yellow urine; jaundice is bilirubin a liver cannot clear. Hemolysis in the vessel spills hemoglobin into the urine (Module 19).

See it move: Scene 3 · EPO, the Kidney’s Order · Scene 4 · Taken Apart by Macrophages

III · Anemia is a sign, polycythemia is a question, and her workup

The notes sort anemia into three mechanisms — too few red cells (hemorrhagic, hemolytic, aplastic or hypoplastic), too little hemoglobin (iron-deficiency, pernicious), abnormal hemoglobin (thalassemia, sickle cell) — and the CBC sorts it by size. Polycythemia is the mirror. Polycythemia vera is a marrow cancer: a JAK2 mutation, the red-cell line proliferating on its own, EPO low because the loop sees too many cells. Secondary polycythemia is a marrow obeying: altitude, smoking, apnoea, lung disease, a high-affinity hemoglobin — or, rarely, an EPO made where it should not be, by a kidney cyst or a tumour, with the sensor silent. Now her workup. Reticulocytes a little up: the factory working harder, steadily. Bilirubin and LDH normal. Iron, B12, folate adequate. Marrow normocellular with a mild erythroid push. JAK2 negative; EPO 44 with a saturation of 98 and a pO₂ of 94; HbA only; no apnoea; no smoke. Output with none of its input. Her marrow is not diseased; it is obeying an order from somewhere the kidney’s oxygen sensor has no part in. Secondary erythrocytosis, cause unclear. The course holds it open.

See it move: Scene 5 · Anemia Is a Sign; Polycythemia Is a Question

3

Watch · explore · think · check

5 scenes. Each one has a short animation or a slide, something to explore, a true/false spot-check of your thinking, and a quick check. Every scene gives you an evidence card for your board.

How to read the scenes

  • Animation (dark teal) — a short animated explainer, one idea each
  • Slide (dark teal) — a still to study: a micrograph, a diagram or a map
  • Explore (purple) — something to push on while you watch
  • Game (purple) — a quick challenge
  • Think (gold) — reason it out, then spot-check yourself with a few true/false questions; not graded
  • Check (gold) — a quick H5P that scores itself

Scene 1 of 5

Stem Cell to Disc

Red marrow, the sinusoid, six stages — and the organelles ejected only after the hemoglobin is built.

Animation · in production · 1 min 50 s

Stem Cell to Disc

A femur; red marrow in the flat bones and proximal epiphyses; a section — reticular framework, sinusoids, hematopoietic cords, a megakaryocyte. The lineage: hemocytoblast → myeloid stem cell → proerythroblast (EPO receptors appear) → erythroblast (ribosomes, iron) → normoblast (hemoglobin fills; nucleus ejected) → reticulocyte (blue net; through the sinusoid wall; 1–2 days) → disc. Fifteen days; two million a second. Supplies in: iron on transferrin, B12, folate.

Prefer the full lecture? Erythropoiesis (original video on the site) · histology page: Bone Marrow

Game

Build a red cell

Assembly line

Six stations from stem cell to disc. Order the cells by their looks, call what each station adds or removes before the line rolls, starve the line three ways and flood it once, then find the factory floor on two marrow sections.

Text description of this game

An assembly line in safety yellow and graphite. Step 1: six drawings of cells from the line, out of order, each with its look in words: large with a big round nucleus filling it and a thin rim of pale cytoplasm; still large with a nucleolus and a blue rim studded with receptors; smaller with a darker nucleus and deep blue grainy cytoplasm; small with a tiny dense black nucleus at one edge and pinkish cytoplasm; no nucleus, pink with a faint blue net when stained; a disc with a pale center. Move them into order from the stem cell to the finished cell with up and down buttons. Step 2: the conveyor with six numbered stations and their names (hemocytoblast, proerythroblast, erythroblast, normoblast, reticulocyte, erythrocyte), a dashed sinusoid wall between stations 4 and 5, and a drawing of the cell at each station. For six items (EPO receptors, ribosomes, iron, hemoglobin, the nucleus, mitochondria) choose the station where it changes most (proerythroblast, erythroblast, normoblast, or reticulocyte on its way to a disc) and whether it is gained or lost there. After you commit each station is labeled with its change, iron appears in the erythroblast and the nucleus is drawn leaving the normoblast. Step 3: the line fed by three supplies, EPO, B12 and folate, and iron, each open or cut off, with a tray for the cells that come out. Choose the supply (full, no iron, no B12 or folate, no EPO from failing kidneys, or too much EPO with supplies full), predict the cells that come out (normal discs in normal numbers; fewer, small and pale; fewer and large; fewer but normal; or more and normal), then run the line: a marker shows where it stalls, the tray fills with the cells, and a readout gives the size (MCV), hemoglobin per cell and reticulocytes (teaching model for batch sizes). Step 4: two of the site’s marrow sections stacked, slide 050 at lower power and slide 048 at higher power, with five numbered pins to name from a list (megakaryocyte, osteoclast, adipocyte, hematopoietic cord, sinusoid): pin 1 on a giant cell with pink cytoplasm and a lobed nucleus, pin 2 inside a round white space, pin 3 on packed small cells, pin 4 inside a thin-walled vessel, pin 5 on crowded cells beside that vessel.

Think · not graded

Commitment means acquiring EPO receptors: only the committed cells and their descendants can hear the order. If the order is loud and everything else is normal, what should the reticulocyte count do — and what would it do instead if the marrow itself were the disease?

Spot-check your thinking: true or false?

Check · Drag the Words

Put the five stages of erythropoiesis in order after the stem cell.

Evidence card 1

Add it to your evidence board

Six stations, fifteen days, two million a second — and only the committed cells can hear the order.

Scene 2 of 5

Counting the Factory’s Speed

The reticulocyte: a supravital stain, a blue net, and the number that says whether the marrow is answering.

Slide · in production

The Reticulocyte Count

A low count in anemia means the factory cannot answer; a high one means it is. Hers is answering an order, steadily.

Prefer the full lecture? Erythropoiesis (original video on the site)

Game

Count the reticulocytes

Tally counter

A hand tally counter and a drop of blood. Stain and count three of the simulator’s patients, add Stina, then ask what the count cannot tell you. The full simulator is linked at the end.

Text description of this game

A hand tally counter look in chrome and methylene blue. Each figure is a round microscope field of about 100 red cells beside two chrome tally counters, one for cells counted and one for reticulocytes. Step 1: choose a patient (Maria before iron, Maria 7 days after iron, or a healthy control) and a stain (New methylene blue, a supravital stain on living cells, or Wright’s stain on a dried smear). Predict what the count will say about the marrow (too low for an anemia, so the marrow cannot answer; in range with no anemia, a steady factory; corrected above 2, answering hard; or nothing to count, because this stain does not show the net), then stain and count: reticulocytes show a dark blue net, the counters fill, and a readout gives the reticulocytes per 1,000 cells, the percentage, the hematocrit and the corrected count (percentage × hematocrit ÷ 45). Maria’s 0.8% and the control’s 1.5% are the simulator’s; the other numbers are a teaching model. Step 2: Stina’s 2015 field, not yet stained, with blank counters. Knowing her supplies are fine, her EPO is 44 (high) and she has no anemia (hematocrit 49%), choose her count and corrected count: about 0.5%; about 1.8% and corrected about 2.0; over 5%, like Maria after iron; or about 1.8% and corrected lower, about 1.6. After you commit the field is stained and the counters read 1,000 cells and 18 reticulocytes. Step 3: two counters side by side, Stina (18 per 1,000) and a polycythemia vera patient at the same hematocrit (blank). Predict that patient’s count; after you commit it reads 16 per 1,000 (teaching model), with EPO and JAK2 shown under each: Stina, EPO 44 and JAK2 negative; polycythemia vera, EPO low and JAK2 positive. Step 4: write why the count cannot tell the two apart and which two lines can, then compare with a model answer. A link at the end opens the site’s Reticulocyte Count Simulation: Reticulocyte Count Simulation.

Think · not graded

Maria’s marrow could not answer her anemia until it had iron; a week later it did. Stina’s marrow is answering with no anemia at all. What does a steady 1.8% say about how loud the order is — and about whether the marrow is the one shouting?

Spot-check your thinking: true or false?

Check · Fill in the Blanks

Read the factory’s speed.

Evidence card 2

Add it to your evidence board

A steady 1.8%: a factory answering an order, not a factory on fire.

Scene 3 of 5

EPO, the Kidney’s Order

The organ that senses oxygen and orders more carriers is the kidney — and it never counts cells.

Animation · in production · 2 min

EPO, the Kidney’s Order

Interstitial fibroblasts in the kidney cortex; oxygen falls; the enzyme that degrades HIF stops; HIF accumulates; the EPO gene switches on. EPO to the marrow; committed cells respond; production up to tenfold; the pipeline’s lag. The see-saw: hypoxia → EPO → marrow → more cells → more oxygen → HIF degraded → EPO off. “Can they do their job?” — the loop counts oxygen, not cells. Renal failure at half a count; testosterone; altitude; doping. Her pair: saturation 98, EPO 44 — the loop’s output with none of its input.

Prefer the full lecture? Erythropoiesis (original video on the site)

Explore

Run the loop

Control room

A see-saw between hypoxia and oxygen delivered, two meters and the kidney’s order. Drop the oxygen four ways, raise the hematocrit by hand, let the marrow run alone, then predict an order from nowhere and lay her chart beside it.

Text description of this explore

A night-blue control room. Each figure has two analog meters across the top (EPO in mIU/mL, 0 to 60, green band 4–26; hematocrit, 20 to 60%, green band 36–46), a see-saw between them with a “hypoxia” box on the left end and an “O₂ delivered” box on the right, and below them Amy’s kidney drawing, a bone with red marrow, and an amber EPO arrow from kidney to marrow that thickens with more EPO. Step 1: choose what drops the oxygen (two months at 4,000 m; a bleed of about a liter, once; a smoker’s carbon monoxide; sleep apnea) for a healthy woman starting at hematocrit 42% and EPO 10 (teaching model). Predict the course (EPO up in days, reticulocytes in a week, hematocrit climbs and stays up; the same, but the hematocrit returns to where it started and EPO switches off; hematocrit first, then EPO; or EPO flat because the kidney counts cells), then run the loop: the see-saw rebalances, the needles move, three charts trace EPO, reticulocytes and hematocrit over 8 weeks, and a readout gives the daytime pulse oximeter reading, EPO at day 2 and week 6, reticulocytes at week 1 and the hematocrit at week 6. Step 2: raise the hematocrit by transfusion with a slider (42 to 60%) and predict what the kidney does to EPO (falls, stays, or rises); the run moves the EPO needle and the readout adds reticulocytes and, above 52%, a viscosity warning. Step 3: polycythemia vera, the bone tagged “JAK2 on” and the hematocrit at 56%: predict the EPO; after you commit the needle reads about 2, below the band. Step 4: a kidney cyst making EPO on its own. For six lines (O₂ saturation, EPO, JAK2, carboxyhemoglobin, reticulocytes, hematocrit) choose low, normal or negative, or high; after you commit a table fills in the cyst’s pattern beside her 2015 chart: saturation 98% (pO₂ 94), EPO 44, JAK2 V617F negative, carboxyhemoglobin 1%, reticulocytes 1.8% (corrected 2.0), hematocrit 49%.

Think · not graded

The loop counts oxygen, not cells. In polycythemia vera the cells are high and the EPO is low — the sensor is doing its job. In her the cells are high and the EPO is high with the sensor satisfied. Where, logically, can an EPO like that come from — and why is that a question for an imaging suite rather than a marrow?

Spot-check your thinking: true or false?

Check · Multiple Choice

Identify what EPO is, where it comes from, and what it does.

Evidence card 3

Add it to your evidence board

A loop that counts oxygen, not cells; hers produces its output with none of its input.

Scene 4 of 5

Taken Apart by Macrophages

Three arrows leave the macrophage — and two of them loop straight back.

Slide · in production

The Recycling Plant

Globin and iron go back; only the heme ring leaves the body — as the colour of a bruise, of bile, of feces.

Prefer the full lecture? Erythrocyte Breakdown (original video on the site)

Explore

Follow the three arrows

Recycling plant

A macrophage, a worn red cell and three exits. Route each part before the map draws, run the plant too fast, burst cells in the vessel, then read her own destruction end.

Text description of this explore

A recycling plant. Step 1: Amy’s drawing of a macrophage (in spleen, liver and marrow) swallowing a worn red cell, with three exits labeled globin, iron and the heme ring, each ending in a dashed box with a question mark. For four parts (the globin’s amino acids; the iron on a day the marrow needs it; the iron on a day the marrow has plenty; the heme ring once the iron is out) choose the destination (new proteins, in the marrow and elsewhere; the marrow, for new heme; stored as ferritin; or the liver, then bile, then out of the body) and the carrier (transferrin; albumin; or none, free or kept inside the cell). After you commit the map draws: globin to amino acids, free in plasma, to new proteins; iron on transferrin (Amy’s Tf drawing) to the marrow or, when spare, into ferritin (Amy’s ferritin drawing); the heme ring to green biliverdin, yellow bilirubin on albumin, the liver (Amy’s liver drawing), bile and gut bacteria, then brown stercobilin in feces and yellow urobilin in urine. Step 2: a dashboard for a hemolytic anemia, macrophages working three times faster than usual (teaching model): bar meters with low, normal and high zones for bilirubin, LDH and haptoglobin, a urine cup and a skin-and-eyes panel, all hidden. For bilirubin, LDH, haptoglobin, urobilin in the urine and yellow in the skin and eyes, choose down, no change or up; after you commit the meters read bilirubin high, LDH high, haptoglobin low, the urine darker, and Amy’s drawing of an eye with yellow whites appears. Step 3: red cells bursting inside a vessel (two drawn splitting open), haptoglobin mopping up, arrows to a kidney and a urine cup whose color is hidden; choose what the urine shows (red-brown with hemoglobin but no red cells; red cells, hematuria; clear, because hemoglobin is too big to filter; bright yellow with bilirubin). After you commit the cup is red-brown with a note: microscope, no red cells. Step 4: her 2015 destruction panel on the same dashboard: bilirubin 0.7 mg/dL in the normal zone, LDH normal, haptoglobin high, urine normal, the whites of the eyes white, and a note: spleen 13 cm with normal counts, reticulocytes 1.8%, ferritin 220 and CRP high (acute phase). Support or refute a classmate’s claim that her spleen is destroying red cells too fast.

Think · not graded

Her haptoglobin is high and her bilirubin is normal. Haptoglobin falls in hemolysis because it binds free hemoglobin — and rises in inflammation. Which reading wins in her, and why does a normal bilirubin settle the destruction end of the balance?

Spot-check your thinking: true or false?

Check · Drag the Words

Trace where each part of a dismantled red cell goes.

Evidence card 4

Add it to your evidence board

Destruction normal — bilirubin 0.7, LDH normal — so the surplus is made, not spared.

Scene 5 of 5

Anemia Is a Sign; Polycythemia Is a Question

Three mechanisms, three sizes, two polycythemias — and her workup, line by line.

Animation · in production · 2 min

Her Workup, Line by Line

The notes’ three mechanisms: not enough cells (hemorrhagic, hemolytic, aplastic); not enough hemoglobin (iron, pernicious — Maude); abnormal hemoglobin (thalassemia, sickle). The CBC’s three sizes. The paradox: a high hematocrit that is still anemic. Then polycythemia: vera (JAK2, EPO low, marrow on its own) vs secondary (EPO high with a reason — altitude, smoke, apnoea, a high-affinity Hb — or EPO made where it should not be). Her lines: retic 1.8; bilirubin normal; supplies fine; JAK2 negative; EPO 44 at 98%; HbA; marrow normocellular. The honest sentence: secondary erythrocytosis, cause unclear — held open.

Prefer the full lecture? Anemia (original video on the site)

Game

Sort the counts

Report desk

A deck of nine patient tiles. Predict two lines on each before it flips, then sort the whole deck into the notes’ three anemia mechanisms and two polycythemias, and find the one tile that fits no slot.

Text description of this game

A report desk with a deck of patient tiles. Each tile’s back, hidden until you commit, carries a small smear sketch and six lab lines: hematocrit, MCV, reticulocytes, bilirubin, EPO and JAK2 (teaching-model values, except Stina’s, which are her 2015 chart). Step 1: five anemia tiles: Maria, from the site’s hemoglobin lab, tired and pale on a diet short of iron; Maude, the site’s pernicious-anemia case, with no intrinsic factor; a sickle-cell crisis; a hemolytic anemia with helmet cells from a mechanical heart valve; and kidney failure on dialysis. For each choose the MCV (small, under 80 fL; normal, 80–100; large, over 100) and the reticulocytes (low, the marrow not answering; or high, answering hard). The backs read: Maria 30%, 70 fL, 0.8%, bilirubin 0.5, EPO high; Maude 27%, 118 fL, 0.6%, bilirubin 1.6, EPO high; sickle crisis 22%, 86 fL, 12%, bilirubin 3.6, EPO high; helmet cells 29%, 92 fL, 7.5%, bilirubin 2.4, EPO high; kidney failure 28%, 88 fL, 0.5%, bilirubin 0.5, EPO low for the anemia; JAK2 negative in all five. Step 2: four high-count tiles: an altitude runner after six weeks at a training camp; polycythemia vera (itching after a hot shower, a ruddy face, a large spleen); a heavy smoker, carboxyhemoglobin 8%; and Stina in 2015 (non-smoker, sea level, no sleep apnea, saturation 98%, HbA only). For each choose the EPO (low, normal, high) and the JAK2 (positive or negative). The backs read: runner 51%, EPO a little high, JAK2 negative; polycythemia vera 58%, EPO low, JAK2 V617F positive; smoker 52%, EPO a little high, JAK2 negative; Stina 49%, MCV 88, reticulocytes 1.8% (corrected 2.0), bilirubin 0.7, EPO 44 (high), JAK2 V617F negative. Step 3: all nine tiles, each with its key values, to sort into six slots: too few cells; too little hemoglobin in each cell; abnormal hemoglobin; primary polycythemia, the marrow on its own; secondary, an order with a known reason; or fits no slot yet.

Think · not graded

Polycythemia vera: high cells, low EPO, JAK2 positive. Altitude: high cells, high EPO, a reason. Hers: high cells, high EPO, JAK2 negative, no reason. Write the one sentence the hematologist wrote — and say what the course does with a finding that fits nothing.

Spot-check your thinking: true or false?

Check · Multiple Choice

Sort the anemias into their three mechanisms.

Evidence card 5

Add it to your evidence board

Three anemia mechanisms, two polycythemias — and one workup that fits none of the slots: secondary erythrocytosis, cause unclear.

4

Your evidence board

Every scene gave you an evidence card, and the chart adds more. Sort each card into the column it supports: An honest marrow obeying an order from elsewhere, Neither on its own, or A marrow disease, or a reason for the oxygen sensor to fire. Some cards can honestly go in more than one place — that’s allowed, and the feedback tells you which cards decide the case.

5

Your verdict

Time to decide. Look back at your bet, then build your verdict from statements that hold up — no writing needed.

Look back at your prediction

Marrow, iron and spleen all normal — where can the extra red cells be coming from?

Find the one you chose at the top. Does the evidence support it, refute it, or revise it?

  • A marrow that has gone its own way — a myeloproliferative disease like polycythemia vera
  • Tissues that are starving despite a normal saturation — a hemoglobin that will not let go
  • An honest marrow obeying an EPO that is being made somewhere it should not be

Build your verdict · no writing

Choose the statement that holds in each set. The ones you keep become your argument.

6

The finding

Finding · EPO-driven over-production, machinery intact

A Factory Obeying a Bad Order

Reticulocytes 1.8%, bilirubin 0.7, iron and B12 adequate, marrow normocellular with a mild erythroid push and 6% plasma cells, red-cell mass 36 mL/kg, JAK2 negative, HbA only, no apnoea, no smoke — and an EPO of 44 beside a saturation of 98. Chart entry: the loop is producing its output with none of its input; the marrow is not diseased, it is obeying an order the kidney’s oxygen sensor had no part in — a secondary erythrocytosis, cause unclear, held open on purpose and seeding a differential a later module names. The next chapter leaves the red cell for the fragment that seals a tear, and the count that climbs with her flares.

Next · Chapter 5

The Clotting Story

Red cells carry oxygen, but when a vessel tears a different system springs into action — fragments of a giant cell, a cascade that runs on calcium and vitamin K, and a platelet count that rises with every one of her flares.

Continue to Chapter 5 →

Reliable information on rare diseases

NORD · NIH GARD · Orphanet · MedlinePlus Genetics: FMF · FMF & AID Global Association · Autoinflammatory Alliance · Global Genes · Amyloidosis Foundation

Stina has one rare disease. In the United States, about 1 in 10 people live with one of the more than 7,000 known rare diseases. These organizations are where patients, families and clinicians go for trustworthy information.

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← Familial Mediterranean Fever — case home

All pages for Module 14 — Blood

14.0 Module Overview
14.1 The Red Cell Finding That Fits Nothing
14.2 What’s in Blood
14.3 Red Cells and Hemoglobin
14.4 Making and Recycling Red Cells
14.5 The Clotting Story
14.6 The Defenders
14.7 The Acute-Phase Alarm
14.8 Conclusion and Assessment
14.9 Evidence Behind the Case

All Modules
  1. Anatomical Language, Membranes & Homeostasis
  2. Just Enough Chemistry
  3. The Cell & Its Transport
  4. Making Cells & Proteins
  5. The Integumentary System
  6. The Skeletal System
  7. The Muscular System
  8. Nervous Tissue & the Senses
  9. The Spinal Cord
  10. The Brain & the Blood–Brain Barrier
  11. The Autonomic Nervous System
  12. Special Senses (in development)
  13. The Endocrine System
  14. Blood
  15. The Heart
  16. Blood Vessels
  17. The Digestive System
  18. The Respiratory System
  19. The Urinary System
  20. Fluids, Electrolytes & Acid–Base Balance
  21. The Reproductive System
  22. The Immune System

List of terms