Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (300 page)

BOOK: Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis
9.26Mb size Format: txt, pdf, ePub
HEMOGLOBIN S–HEMOGLOBIN C DISEASE
   Definition

A moderately severe sickling disease, clinically intermediate between sickle cell anemia and sickle cell trait. Occurs in 1 of 833 people of African ancestry.

   Laboratory Findings
   Hb electrophoresis: HbA is absent; HbS and HbC are present in approximately equal amounts. HbF is ≤6%.
   CBC.
   Anemia: mild to moderate normochromic, normocytic.
   Peripheral blood smear (PBS): tetragonal crystals within the RBC in 70% of patients. Target cells and plump/angulated sickle cells, rather than typical sickle cells, are identified.
   MCV is low, or low normal; MCHC is high.
SICKLE CELL–α-THALASSEMIA DISEASE

α-Thalassemia modifies the severity of sickle cell anemia. Otherwise, it is usually clinically insignificant.

SICKLE CELL–β-THALASSEMIA DISEASE
   Definition

Condition of mild to moderate severity found in 1 of every 1,667 people of African ancestry.

   Laboratory Findings
   Hb electrophoresis: HbS varies between 20% and 90%; HbF between 2% and 20%. If the HbS is very high and HbA1 is suppressed, the disease is severe. In milder cases, HbA1 is 25–50%. HbA2 is increased (due to the presence of β-thalassemia), but it has to be differentiated from HbC, which has a similar migration pattern.
   CBC
   RBC: hypochromic, microcytic anemia with decreased MCV (iron deficiency must be ruled out).
   Peripheral blood smear (PBS): target cells are prominent; other findings resemble those of sickle cell anemia.

Other books

The Tapestry in the Attic by Mary O'Donnell
Seduced and Betrayed by Candace Schuler
Deceived by Stephanie Nelson
The Errant Flock by Jana Petken
Dusted to Death by Barbara Colley
They Marched Into Sunlight by David Maraniss
The Family Man by Trish Millburn
Slave Of Dracula by Barbara Hambly
Hide and Seek by James Patterson