Temporal sequence of splenic dysfunction in sickle cell disease

Abstract

Sickle cell patients develop splenic dysfunction early in the course of their disease as shown by failure to visualize the organ on technetium‐99m colloid scintigraphy. However, preliminary studies from our center have shown that, when the spleen is not demonstrable on colloid uptake, it may be visualized on technetium‐99m heat‐denatured RBC scintigraphy. With time, however, the spleen can no longer be visualized with both tests in many patients. We have studied 46 patients aged 2 to 16 years, which included 36 SS, 7 Sβ0 thal, and 3 SD. Eighteen (39.1%) had normal splenic colloid uptake (Group 1), 15 (32.6%) had partial uptake (Group 2), and 13 (28.3%) had absent uptake (Group 3). When the patients in Group 1 were compared to those in the two other groups, there was no significant difference in the mean age and Hb F values. However, the mean Hb of 10.2 g/dl in Group 1 was significantly higher than the value of 9.0 g/dl in the other two groups. In addition, 60% of the SS patients with normal uptake and 40% of those with partial or absent uptake had co‐existing α‐thal trait; the difference in this proportion is significant (χ2 = 85, P < 0.0001). Heat‐denatured RBC scintigraphy was carried out on five patients in Group 2, and the spleen was visible in all, while of 12 children in Group 3, the spleen was visible only in 4 patients. This study demonstrates that the phagocytic function of the spleen, which is tested by colloid uptake, is the first to be lost while the filtration function, tested by denatured RBC uptake, persists for much longer. This finding may have significant implications for the clinical symptomatology and therapeutic strategies of sickle cell disease. Am. J. Hematol. 69:23‐27, 2002. © 2002 Wiley‐Liss, Inc.

Pattern of Bone Mineral Density in Sickle Cell Disease Patients with the High-Hb F Phenotype

“…We had shown in studies of the spleen and brain that changes related to chronic vasculopathy are rare in pediatric patients. More than 75% of our patients retain good spleen function up to the age of 16 years [28] and only about 3% show evidence of silent brain infarcts [29], while 20% of adult patients had infarcts [30]. We believe this is because the high Hb F in early childhood protects them from vasculopathy.…”

Silent brain infarcts in adult Kuwaiti sickle cell disease patients

“…This contributes significantly to the amelioration of the disease and protects the patients from many of its complications [23]. Overt stroke, chronic leg ulcers, priapism, acute chest syndrome, and early splenic dysfunction are uncommon [16,24,25]. However, a subset of patients exists who have frequent, severe painful crises, many of whom end up with osteonecrosis.…”

Does Elevated Hemoglobin F Modulate the Phenotype in Hb SD-Los Angeles?

“…stroke, leg ulcers, bacterial infections and acute chest syndrome, that are rampant in other populations are either not encountered or mild when they occur [15,16,17,18,19]. Also striking among our patients is the preservation of spleen function till adulthood and the rarity of severe bacterial infections in most patients [17]. However, Kuwaiti Hb SD patients do not fit this pattern, although their Hb F levels are similar and their β S -globin gene was on chromosomes carrying the Arab/Indian haplotype.…”

“…The Hb F is homogeneously distributed in the red blood cells (RBC) [14]. Therefore, the disease is typically mild and patients are not generally symptomatic until after 4 years of age [15,16,17,18,19]. …”