Differential Diagnosis

The patient's presentation of sudden onset joint and abdominal pain, along with a known hemoglobin (Hb) disorder, suggests several potential diagnoses. The laboratory results provided, including a low hemoglobin level and elevated platelet count, help to narrow down the differential diagnosis.

• Single Most Likely Diagnosis

  • Sickle Cell Crisis: Given the patient's known Hb disorder and symptoms of joint and abdominal pain, sickle cell crisis is the most likely diagnosis. Sickle cell disease is a genetic disorder that affects hemoglobin production, leading to abnormal red blood cells that can cause episodes of pain due to vaso-occlusion. The patient's low hemoglobin level and elevated platelet count are consistent with this diagnosis.

• Other Likely Diagnoses

  • Vaso-occlusive Crisis in Other Hemoglobinopathies: While sickle cell disease is the most common cause of vaso-occlusive crises, other hemoglobinopathies (like HbC disease or HbS-beta thalassemia) could also present similarly.
  • Infection: Patients with sickle cell disease are at increased risk of infections, which can precipitate a crisis or present with similar symptoms.

• Do Not Miss Diagnoses

  • Acute Appendicitis: Abdominal pain in a child requires consideration of appendicitis, which is a surgical emergency. Although the patient's known Hb disorder and symptoms suggest a sickle cell crisis, appendicitis must be ruled out due to its potential for severe consequences if missed.
  • Splenic Sequestration Crisis: This is a life-threatening complication of sickle cell disease where red blood cells are trapped in the spleen, leading to severe anemia and potentially shock. It's crucial to consider this diagnosis in patients with sickle cell disease presenting with acute symptoms.

• Rare Diagnoses

  • Other Rare Hemoglobinopathies: There are numerous rare hemoglobinopathies that could potentially cause similar symptoms, though they are less likely given the patient's presentation and known history.
  • Thalassemia Major with Superimposed Infection or Crisis: Though less common in this context, thalassemia major (Cooley's anemia) could potentially present with similar symptoms, especially if complicated by an infection or a hemolytic crisis.