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The red cell storage lesion

14 min

Skills you'll build3 skills
  • Explain acidification and ATP changes during refrigerated red-cell storage
  • Predict the supernatant potassium change in refrigerated red cells
  • Match red-cell glycolysis and the pentose phosphate pathway to what each supplies

Try first

Try first

The supernatant pH of a stored red-cell unit falls from 6.97 on day 1 to 6.55 on day 35. The refrigerator record shows 1 to 6 °C throughout, with no alarms. What explains the fall?

Right. Keep going to follow the reasoning.

Keep going to see the reasoning.

Keep going to see the reasoning.

Keep going to see the reasoning.

Get the idea

Use the explanation to check your first decision.

Red-cell metabolism during storage

Refrigeration at 1 to 6 °C slows red-cell metabolism, and glycolysis continues through storage. The cells consume glucose and produce lactate and hydrogen ions, so the pH of the unit falls.1,2 Adenosine triphosphate (ATP) may rise during the first week and then declines with prolonged storage. 2,3-Bisphosphoglycerate (2,3-BPG) falls during conventional storage, which raises hemoglobin's oxygen affinity until the cells rebuild it after transfusion.1,2

Potassium and sodium shifts

ATP-dependent pumps keep potassium high and sodium low inside the red cell. Cold slows these pumps, so potassium leaks into the supernatant and sodium enters the cells.1,3 Supernatant potassium rises with storage time. The rise matters most when a large extracellular volume is transfused rapidly or to a small recipient such as a neonate.1,3

Glycolysis and the pentose phosphate pathway

Mature red cells have no mitochondria. Embden-Meyerhof glycolysis supplies nearly all their ATP, which powers the cation pumps and keeps the membrane flexible. The pentose phosphate pathway supplies reduced nicotinamide adenine dinucleotide phosphate (NADPH). NADPH keeps glutathione reduced, and reduced glutathione protects hemoglobin and membrane proteins from oxidation.1,2

Finding in the unitDirection during storageWhat drives it
Glucose and pHFallGlycolysis continues and acid accumulates
LactateRisesThe end product of glycolysis
ATPMay rise in the first week, then fallsEarly glycolysis, then acidification and substrate loss
2,3-BPGFallsAcidification slows its synthesis
Supernatant potassiumRisesCold slows the ATP-dependent pumps
Free hemoglobin and percent hemolysisRiseMembrane injury and cell rupture

Reading a storage record

The rate of change varies from unit to unit, so no single value shows that a unit is unsuitable. Release is based on the approved component system, the labeled expiration, the storage record, inspection and quality control.1,4

Follow the bench demonstration

Sources for this step
References
  1. Bloch EM, Campbell-Lee S, McKenna DH Jr, Montemayor-Garcia C, Schwartz J, Shaz B, Storry J, eds. Technical Manual. 22nd ed. AABB; 2026.
  2. Yoshida T, Prudent M, D'Alessandro A. Red blood cell storage lesion: causes and potential clinical consequences. Blood Transfus. 2019;17(1):27-52. doi:10.2450/2019.0217-18
  3. Flatt JF, Bawazir WM, Bruce LJ. The involvement of cation leaks in the storage lesion of red blood cells. Front Physiol. 2014;5:214. doi:10.3389/fphys.2014.00214
  4. AABB, American Red Cross, America's Blood Centers, Armed Services Blood Program. Circular of Information for the Use of Human Blood and Blood Components. June 2024. Accessed September 27, 2026.

Watch one

Read each decision and its explanation.

A laboratory professional in quality control reviews the storage study for one red-cell unit in AS-1 additive solution. The product specification for end-of-storage hemolysis is below 1%.

MeasurementDay 1Day 7Day 35
Storage temperature1–6 °C, no alarms1–6 °C, no alarms1–6 °C, no alarms
Supernatant pH6.976.826.55
Supernatant lactate4 mmol/L11 mmol/L29 mmol/L
ATP4.4 µmol/g Hb4.8 µmol/g Hb3.3 µmol/g Hb
2,3-BPG12.5 µmol/g Hb5.0 µmol/g Hb0.4 µmol/g Hb
Supernatant potassium3 mmol/L13 mmol/L38 mmol/L
Hemolysis0.05%0.08%0.31%

Does the record suggest a faulty unit?

  1. Check the storage record first. It shows 1 to 6 °C at every point, with no alarms.

    Storage changes can be interpreted only when the unit stayed within its labeled conditions.

  2. pH falls from 6.97 to 6.55 as lactate rises from 4 to 29 mmol/L, the expected pattern.

    Falling pH with rising lactate shows glycolysis continuing in the cold.

  3. ATP rises from 4.4 to 4.8 µmol/g Hb by day 7, then falls to 3.3 µmol/g Hb, which is also expected.

    ATP can rise in the first week before acid and substrate loss bring it down.

  4. 2,3-BPG falls from 12.5 to 0.4 µmol/g Hb, an expected change in conventional storage.

    2,3-BPG falls early in conventional storage.

  5. Supernatant potassium rises from 3 to 38 mmol/L, as expected with storage time.

    Cold slows the pumps, so potassium leaks out with time.

  6. Hemolysis on day 35 is 0.31%, below the 1% specification.

    Hemolysis is the value with a product specification.

No. The record shows the expected storage lesion in a unit kept at 1 to 6 °C, and hemolysis of 0.31% meets the specification. The day-7 ATP above day 1 is the expected early rise.

Practice this skill

Your turn

Problem 1 of 3 · Hints available

Which description best preserves the time course of ATP during conventional red-cell storage?

Incorrect. ATP may rise early, and its trajectory depends on storage conditions and duration.

Correct. Early glycolytic activity can support a rise before progressive acidification and metabolic impairment lower ATP.

Incorrect. ATP changes throughout storage. The expiration date does not mark the beginning of ATP depletion.

Hint
  1. Glycolysis keeps running in the first days of storage.
  2. Compare the first week of storage with the last.

Review Changes during refrigerated storage

Problem 2 of 3 · Hints available

During conventional refrigerated red-cell storage, which potassium change is expected?

Correct. Potassium leaves stored red cells as cold temperature slows cation transport.

Incorrect. Refrigeration slows transport and metabolism, allowing potassium to accumulate outside stored red cells.

Incorrect. Cold temperature slows ATP-dependent transport, so potassium accumulates outside the cells.

Hint
  1. Name what keeps potassium inside a red cell.
  2. Ask what powers the pumps that keep potassium inside the cell.

Review Membrane and cation control

Problem 3 of 3 · On your own

A stored red cell keeps its glutathione reduced as long as it can make NADPH. Which pairing of red-cell pathway and supply is right?

The pathways are reversed. Glycolysis supplies nearly all red-cell ATP, and the pentose phosphate pathway supplies NADPH.

Assigned the main ATP supply to the pentose pathway

Mature red cells lack mitochondria, so Embden-Meyerhof glycolysis supplies nearly all of their ATP. The pentose phosphate pathway makes NADPH, which keeps glutathione reduced. Attributing ATP to the pentose pathway misses its role in protecting hemoglobin and membrane proteins from oxidation.

Mature red cells have no mitochondria, so oxidative phosphorylation supplies none of their ATP.

Embden-Meyerhof glycolysis supplies the ATP for the pumps and membrane. The pentose phosphate pathway supplies the NADPH that keeps glutathione reduced.

The Rapoport-Luebering shunt makes 2,3-BPG, the regulator of oxygen affinity. NADPH comes from the pentose phosphate pathway.

Review Metabolic support

Use it

Read the case evidence, then make each decision. The step is complete without it.

  • Grace Staines, the day-shift laboratory professional in quality control, reviews end-of-storage testing on one AS-1 red-cell unit for the monthly quality-control record.
  • The unit stayed at 1 to 6 °C for 42 days, with no alarms.
  • On day 5 of the same study, ATP read 4.9 µmol/g Hb.
  • A student on rotation asks about the record.
TestResultPreviousReference intervalFlag
Supernatant pH6.48Day 1: 6.976.97Day 1
ATP3.1 µmol/g HbDay 1: 4.5 µmol/g Hb4.5 µmol/g HbDay 1
Supernatant potassium44 mmol/LDay 1: 3 mmol/L3 mmol/LDay 1
Hemolysis0.42 %Day 1: 0.04 %0.04 %Day 1Below 1% %Below 1%

Specimen: Not measured on this component. AS-1 red cells, supernatant tested on day 42 of storage

Decision 1 of 2

The student asks whether the day-5 ATP, higher than day 1, shows a fault in the unit. What does Grace answer?

ATP can rise during the first week of storage, when glycolysis is still brisk. A day-5 value above baseline is an expected change.

Assumed ATP falls from the start of storage

Glycolysis continues in the cold, consuming glucose and producing lactate, so pH falls steadily through storage. ATP can rise during the first week before it declines with prolonged storage, so an early ATP value above baseline is an expected storage change and does not indicate a defective unit.

Early glycolysis can raise ATP. Acidification and substrate loss bring it down later, as the day-42 value of 3.1 µmol/g Hb shows.

ATP changes throughout storage. It rose by day 5 and fell by day 42.

Review Changes during refrigerated storage

Decision 2 of 2

The student asks why supernatant potassium rose to 44 mmol/L in a unit kept cold. What does Grace answer?

The storage record shows 1 to 6 °C throughout. Cold slows the potassium pumps, and the leak is the expected result.

Predicted that cold storage prevents potassium leakage

Refrigeration slows the ATP-dependent pumps that keep potassium inside red cells, so potassium leaks into the supernatant and accumulates with storage time. The potassium load is most significant when a large volume of supernatant is transfused rapidly or into a small recipient such as a neonate.

Hemolysis stayed below 1%. Most of the rise is potassium leaking out of intact cells.

The pumps that keep potassium inside the red cell slow down at 1 to 6 °C. Potassium accumulates in the supernatant with storage time.

Review Membrane and cation control

The storage record showed 1 to 6 °C with no alarms, so the early ATP rise and later fall, the falling pH and the rising potassium are the expected storage lesion. The unit meets its hemolysis specification.

For reference

Sources checked