Correspondence
Volume 162 Number 6
long been recognized in the absence of maternal hemoglobinopathy. They form part of the spectrum of normal placental maturation and senescence from the ninth gestational week onward.' Basement-membrane siderosis alone, even in the setting of maternal 13thalassemia, is not necessarily a significant finding, and the statement of Birkenfeld and coworkers that "positive (iron) staining in the placental villi probably reflects tissue ferritin and hemosiderin deposits that prevent excessive iron transport to the fetus" (emphasis added) is not justified by the data presented. Normal values for placental iron content" and for levels of iron, ferritin, and transferrin saturation in term infant umbilical cord blood' have been defined. Were placental concentrations of iron determined for the pregnancy in question? Was evidence of iron loading sought in the infant? These data might provide valuable information about the regulation of maternofetal iron transport in the presence of maternal hypersideremia. A. S. Knisely, MD Department· of Pathology University of Utah Medical Center Salt Lake City, UT 84132
blue reaction that we have used might not visualize very small amounts of ferritin in the placental villi, whereas sensitive immunohistochemical methods will do so. We believe that taken together, these observations do imply a difference of placental iron load between the normal placentas and the placenta of the thalassemic mother. Although we have not examined the ferritin level in the cord blood, the mere observation of hemosiderin deposits in the placenta of the thalassemic mother probably reflects iron deposits that could have otherwise been transferred to the fetal circulation. A. Birkenfeld, MD N. Mordel, MD Department of Obstetrics and Gynecology E. Okon, MD Department of Pathology Hadassah University Hospital POB 1200 Jerusalem, Israel 91120
REFERENCES I. Okuyama T, Tawada T, Furuya H, Villee CA. The role of
2. REFERENCES I. McKay DG, Hertig AT, Adams EC, Richardson MV. Histochemical observations on the human placenta. Obstet GynecoI1958;12:1-36. 2. Manci EA, Blackburn WR. Regional variations in the levels of zinc, iron, copper, and calcium in the term human placenta. Placenta 1987;8:497-502. 3. Puolakka],Jinne 0, Vihko R. Evaluation by serum ferritin assay of the influence of maternal iron stores on the iron status of newborns and infants. Acta Obstet Gynecol Scand 1980;95(suppl):53-6.
Reply To the Editors: We thank Dr. Knisely for his comments. Publications that describe transferrin and ferritin in the human placenta have applied immunohistochemical methods for the detection of these substances.1.2.3 McKay et al.' have stated that "during the third trimester there is a progressive diminution in the amount of iron deposited in the placental stroma. The subtrophoblastic deposits noted in the second trimester have all but disappeared. A few villi in many term placentas however contain one to several macrophages (Hofbauer cells) which contain ferric but not ferrous iron." We have used the Comori Prussian blue reaction to detect hemosiderin in normal term placentas and were unable to visualize stainable iron in the stroma of the chorionic villi. However, we did show it in the term placenta from a mother suffering from l3-thalassemia major. s It is known that with normal iron stores only trace amounts of hemosiderin are found in the body, mainly in reticuloendothelial cells in the bone marrow, spleen, and liver. In iron-overloaded cells, most of the iron is stored in the form of hemosiderin. The Prussian
1639
3. 4. 5.
transferrin and ferritin in the fetal-maternal-placental unit. AM] OBSTET GYNECOL 1985;152:344-50. Fletcher], Suter PEN. The transport of iron by the human placenta. Clin Sci 1969;36:209-20. Brown P], Johnson PM, Ogbimi AO, Tappin J. A characterization and localization of human placental ferritin. Biochern] 1979; 182:763-9. McKay DG, Hertig AT, Adams EC, Richardson MV. Histochemical observations on the human placenta. Obstet GynecoI1958;12:1-36. Birkenfeld A, Mordel N, Okon E. Direct demonstration of iron in a term placenta in a case of j3-thalassemia major. AM] OBSTET GYNECOL 1989;160:562-63.
Significance of uric acid clearance in preeclampsia To the Editors: Although serum uric acid level is useful for estimating the severity of preeclampsia,' the level of serum uric acid often overlaps between preeclampsia and normal pregnancy.2 Decrease in uric acid clearance in preeclampsia has been known,' but its use in the precise evaluation of preeclampsia has not been reported. We estimate the usefulness of uric acid clearance in various conditions of pregnancy. A total of 33 pregnant women (normal pregnancy, 12; preeclampsia, 10; normal pregnancy with chronic glomerulonephritis, 6; superimposed preeclampsia, 5) were studied. Ages of patients ranged from 23 to 39 years. All clinical and laboratory data were obtained from 38 to 40 weeks' gestation and all patients were delivered of infants at 39 to 40 weeks' gestation. There were no significant differences in serum creatinine levels (normal pregnancy, 0.81 ± 0.02 mg/dl; preeclampsia, 1.00 ± 0.09 mg/dl; normal pregnancy with chronic glomerulonephritis, 1.14 ± 0.09 mg/dl; superimposed preeclampsia, 1.48 ± 0.23 mg/dl; mean ± SEM) or creatinine clearance (normal preg-
1640 Correspondence
.... .... •••• 6
3
:.1 (Fig 1 A)
:
12
SPE
.-
SPE
(Fig 1 B)
9
~ .
12 S-UA (mg/dl) I
---, p, 0.01 --..-l
24 Cu. (ml/min)
,
---,
P 0.01
--..-l
as markers for estimation of the severity of preeclampsia. In conclusion, although there is no conclusive explanation for a decrease in uric acid clearance in preeclampsia," 5 it is one of the most reliable markers for the diagnosis and estimation of the severity of preeclampsia. This index is also useful in the differentiation of superimposed preeclampsia from normal pregnancy with chronic glomerulonephritis. Ashio Yoshimura, Terukuni Ideura, Shigeki Iwasaki, Shozo Koshikawa,
12 S-UA (mg/dl) I
--,
NS
--.J
••• • 6I
N+CGN!
18
.. '
6
N+CGN!
9
~.:t: 6,
:.!
June 1990 Am J Obstet Gynecol
12 I
CU. (ml/min)
15
MD MD MD MD
Department of Internal Medicine Showa University Fujigaoka Hospital 1-30 Fujigaoka, Midori-ku Yokohama 227,Japan
I
--, P 0.01
--.J
Fig. 1. A, Serum uric acid concentration (S-VA) and uric acid clearance (CUA) in normal pregnancy (N) and preeclampsia (PE). D, Serum uric acid concentration (S-UA) and uric acid clearance (CUA) in normal pregnancy with chronic glomerulonephritis (N + CCNY and superimposed preeclampsia (SPE). Bars show mean and shadowed areas show ±SD.
nancy, 148.7 ± 10.2 mllmin; preeclampsia, 121.4 ± 9.3 mllmin; normal pregnancy with chronic glomerulonephritis, 124.3 ± 14.1 mllmin; superimposed preeclampsia, 95.0 ± 17.2 mIl min). Although the serum uric acid level in preeclampsia (7.5 ± 0.61 mg/dl) increased significantly (p
Volume 162 Number 6
long been recognized in the absence of maternal hemoglobinopathy. They form part of the spectrum of normal placental maturation and senescence from the ninth gestational week onward.' Basement-membrane siderosis alone, even in the setting of maternal 13thalassemia, is not necessarily a significant finding, and the statement of Birkenfeld and coworkers that "positive (iron) staining in the placental villi probably reflects tissue ferritin and hemosiderin deposits that prevent excessive iron transport to the fetus" (emphasis added) is not justified by the data presented. Normal values for placental iron content" and for levels of iron, ferritin, and transferrin saturation in term infant umbilical cord blood' have been defined. Were placental concentrations of iron determined for the pregnancy in question? Was evidence of iron loading sought in the infant? These data might provide valuable information about the regulation of maternofetal iron transport in the presence of maternal hypersideremia. A. S. Knisely, MD Department· of Pathology University of Utah Medical Center Salt Lake City, UT 84132
blue reaction that we have used might not visualize very small amounts of ferritin in the placental villi, whereas sensitive immunohistochemical methods will do so. We believe that taken together, these observations do imply a difference of placental iron load between the normal placentas and the placenta of the thalassemic mother. Although we have not examined the ferritin level in the cord blood, the mere observation of hemosiderin deposits in the placenta of the thalassemic mother probably reflects iron deposits that could have otherwise been transferred to the fetal circulation. A. Birkenfeld, MD N. Mordel, MD Department of Obstetrics and Gynecology E. Okon, MD Department of Pathology Hadassah University Hospital POB 1200 Jerusalem, Israel 91120
REFERENCES I. Okuyama T, Tawada T, Furuya H, Villee CA. The role of
2. REFERENCES I. McKay DG, Hertig AT, Adams EC, Richardson MV. Histochemical observations on the human placenta. Obstet GynecoI1958;12:1-36. 2. Manci EA, Blackburn WR. Regional variations in the levels of zinc, iron, copper, and calcium in the term human placenta. Placenta 1987;8:497-502. 3. Puolakka],Jinne 0, Vihko R. Evaluation by serum ferritin assay of the influence of maternal iron stores on the iron status of newborns and infants. Acta Obstet Gynecol Scand 1980;95(suppl):53-6.
Reply To the Editors: We thank Dr. Knisely for his comments. Publications that describe transferrin and ferritin in the human placenta have applied immunohistochemical methods for the detection of these substances.1.2.3 McKay et al.' have stated that "during the third trimester there is a progressive diminution in the amount of iron deposited in the placental stroma. The subtrophoblastic deposits noted in the second trimester have all but disappeared. A few villi in many term placentas however contain one to several macrophages (Hofbauer cells) which contain ferric but not ferrous iron." We have used the Comori Prussian blue reaction to detect hemosiderin in normal term placentas and were unable to visualize stainable iron in the stroma of the chorionic villi. However, we did show it in the term placenta from a mother suffering from l3-thalassemia major. s It is known that with normal iron stores only trace amounts of hemosiderin are found in the body, mainly in reticuloendothelial cells in the bone marrow, spleen, and liver. In iron-overloaded cells, most of the iron is stored in the form of hemosiderin. The Prussian
1639
3. 4. 5.
transferrin and ferritin in the fetal-maternal-placental unit. AM] OBSTET GYNECOL 1985;152:344-50. Fletcher], Suter PEN. The transport of iron by the human placenta. Clin Sci 1969;36:209-20. Brown P], Johnson PM, Ogbimi AO, Tappin J. A characterization and localization of human placental ferritin. Biochern] 1979; 182:763-9. McKay DG, Hertig AT, Adams EC, Richardson MV. Histochemical observations on the human placenta. Obstet GynecoI1958;12:1-36. Birkenfeld A, Mordel N, Okon E. Direct demonstration of iron in a term placenta in a case of j3-thalassemia major. AM] OBSTET GYNECOL 1989;160:562-63.
Significance of uric acid clearance in preeclampsia To the Editors: Although serum uric acid level is useful for estimating the severity of preeclampsia,' the level of serum uric acid often overlaps between preeclampsia and normal pregnancy.2 Decrease in uric acid clearance in preeclampsia has been known,' but its use in the precise evaluation of preeclampsia has not been reported. We estimate the usefulness of uric acid clearance in various conditions of pregnancy. A total of 33 pregnant women (normal pregnancy, 12; preeclampsia, 10; normal pregnancy with chronic glomerulonephritis, 6; superimposed preeclampsia, 5) were studied. Ages of patients ranged from 23 to 39 years. All clinical and laboratory data were obtained from 38 to 40 weeks' gestation and all patients were delivered of infants at 39 to 40 weeks' gestation. There were no significant differences in serum creatinine levels (normal pregnancy, 0.81 ± 0.02 mg/dl; preeclampsia, 1.00 ± 0.09 mg/dl; normal pregnancy with chronic glomerulonephritis, 1.14 ± 0.09 mg/dl; superimposed preeclampsia, 1.48 ± 0.23 mg/dl; mean ± SEM) or creatinine clearance (normal preg-
1640 Correspondence
.... .... •••• 6
3
:.1 (Fig 1 A)
:
12
SPE
.-
SPE
(Fig 1 B)
9
~ .
12 S-UA (mg/dl) I
---, p, 0.01 --..-l
24 Cu. (ml/min)
,
---,
P 0.01
--..-l
as markers for estimation of the severity of preeclampsia. In conclusion, although there is no conclusive explanation for a decrease in uric acid clearance in preeclampsia," 5 it is one of the most reliable markers for the diagnosis and estimation of the severity of preeclampsia. This index is also useful in the differentiation of superimposed preeclampsia from normal pregnancy with chronic glomerulonephritis. Ashio Yoshimura, Terukuni Ideura, Shigeki Iwasaki, Shozo Koshikawa,
12 S-UA (mg/dl) I
--,
NS
--.J
••• • 6I
N+CGN!
18
.. '
6
N+CGN!
9
~.:t: 6,
:.!
June 1990 Am J Obstet Gynecol
12 I
CU. (ml/min)
15
MD MD MD MD
Department of Internal Medicine Showa University Fujigaoka Hospital 1-30 Fujigaoka, Midori-ku Yokohama 227,Japan
I
--, P 0.01
--.J
Fig. 1. A, Serum uric acid concentration (S-VA) and uric acid clearance (CUA) in normal pregnancy (N) and preeclampsia (PE). D, Serum uric acid concentration (S-UA) and uric acid clearance (CUA) in normal pregnancy with chronic glomerulonephritis (N + CCNY and superimposed preeclampsia (SPE). Bars show mean and shadowed areas show ±SD.
nancy, 148.7 ± 10.2 mllmin; preeclampsia, 121.4 ± 9.3 mllmin; normal pregnancy with chronic glomerulonephritis, 124.3 ± 14.1 mllmin; superimposed preeclampsia, 95.0 ± 17.2 mIl min). Although the serum uric acid level in preeclampsia (7.5 ± 0.61 mg/dl) increased significantly (p
