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The red cell storage lesion

14 min

  • 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

Read the full reference

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. The next section explains why.

The next section explains it.

The next section explains it.

The next section explains it.

Get the idea

Metabolism continues in the cold

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 leaks out

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 climbs 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

Two pathways, two supplies

Mature red cells have no mitochondria. Embden-Meyerhof glycolysis supplies nearly all their ATP, which runs 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 builds up
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 rests on the approved component system, the labeled expiration, the storage record, inspection and quality control.1,4

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

A quality-control technologist 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 point to a faulty unit?

  1. Storage record first: 1 to 6 °C at every point, with no alarms.

    A storage change means something only when the unit stayed in its labeled conditions.

  2. pH falls from 6.97 to 6.55 as lactate rises from 4 to 29 mmol/L. Expected.

    Falling pH with rising lactate is glycolysis still running 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. 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. Expected.

    2,3-BPG falls early in conventional storage.

  5. Supernatant potassium rises from 3 to 38 mmol/L. Expected.

    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 the product specification judges.

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.

Your turn

Problem 1 of 3

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

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 hold potassium inside the cell.

Review Membrane and cation control

Problem 3 of 3

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 pairs are swapped. 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. Crediting it with ATP obscures why low NADPH leaves hemoglobin and membrane proteins open to 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

  • Grace Adeyemi, the day-shift quality-control technologist, 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 pH6.486.97Day 1
ATP3.1 µmol/g Hb4.5 µmol/g HbDay 1
Supernatant potassium44 mmol/L3 mmol/LDay 1
Hemolysis0.42 %0.04 %Day 1Below 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 must fall from the first moment 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 point to a faulty 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 rise matters most when a large extracellular volume is transfused rapidly or to 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 hold 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 clue that settled this case is the storage record at 1 to 6 °C with no alarms. With the conditions in order, the early ATP rise and later fall, the falling pH and the rising potassium are the expected storage lesion. The unit is then judged on its hemolysis specification, which it meets.

Keep

Sources checked