Les transfusions sanguines répétées sont fréquemment nécessaires chez les patients atteints d’hémopathies ou de pancytopénie induite par la chimiothérapie. Elles peuvent cependant entraîner des complications métaboliques, notamment une hypocalcémie liée au citrate utilisé comme anticoagulant dans les produits sanguins labiles.

Un homme de 67 ans présentant une pancytopénie secondaire à un cancer pulmonaire a reçu des transfusions répétées après un séjour prolongé en réanimation. Le bilan biologique montrait une hypocalcémie profonde associée à une hypomagnésémie sévère. Le traitement par gluconate de calcium intraveineux puis supplémentation orale a permis la correction des anomalies. Malgré un pH artériel normal, l’analyse physicochimique selon Stewart mettait en évidence des troubles métaboliques complexes compatibles avec une accumulation de citrate.

Les transfusions répétées peuvent induire une hypocalcémie significative. Le dosage du calcium ionisé et l’analyse physicochimique permettent d’identifier des anomalies métaboliques malgré un pH normal.

Repeated blood transfusions are commonly required in patients with hematological disorders or chemotherapy-induced bone marrow suppression. However, transfusion therapy may lead to metabolic complications, including hypocalcemia related to citrate used as an anticoagulant in stored blood products. Citrate chelates ionized calcium and magnesium, and large citrate loads may exceed the body's metabolic capacity, leading to clinically significant electrolyte disturbances.

We report the case of a 67-year-old man with chemotherapy-induced pancytopenia secondary to lung cancer who required repeated blood transfusions following a prolonged intensive care unit stay for severe community-acquired pneumonia. Laboratory investigations revealed profound hypocalcemia associated with severe hypomagnesemia and vitamin D deficiency. Urgent treatment with intravenous calcium gluconate followed by oral calcium, vitamin D, and magnesium supplementation led to normalization of electrolyte levels. Interestingly, arterial blood gas analysis showed a near-normal pH, which could have been interpreted as the absence of significant acid–base disturbance using conventional methods. However, physicochemical analysis using the Stewart approach revealed complex metabolic abnormalities, including an increased strong ion difference and an elevated strong ion gap, most likely related to circulating citrate derived from repeated transfusions. These abnormalities were further illustrated using a Gamblegram representation.

Repeated blood transfusions may lead to clinically significant hypocalcemia due to citrate accumulation. Careful monitoring of calcium and magnesium levels is therefore essential. Physicochemical analysis of acid–base balance may also help identify complex metabolic disturbances that could remain undetected with conventional approaches.