Plasma erythropoietin in polycythemia.

Erythropoietin titers of plasma cannot be used to differentiate polycythemia vera from secondary polycythemia since the limit of sensitivity of our current bioassay technics is 50 mU, considerably higher than levels found in normal subjects and in patients with polycythemia. However, erythropoietin is relatively heat stable, and since abundant plasma is available from therapeutic phlebotomies it is possible to prepare and assay highly concentrated, erythropoietin-containing extracts. In 35 normal subjects, erythropoietin levels ranged from less than 5 mU/ml (the limit of sensitivity) to 18 mU/ml with a mean of 7.8 mU/ml. In 21 patients with proved polycythemia vera, the levels were less than 5 mU/ml in all. In 41 patients with suspected secondary polycythemia or polycythemia of unknown origin, the levels ranged from less than 5 to 3,000 mU/ml. Three of the 11 patients with levels less than 5mU/ml were subsequently shown to have polycythemia vera. These results suggest that this refinement of the routine bioassay for erythropoietin may be of clinical importance in the differential diagnosis of polycythemia.     

Tissue plasminogen activator levels in different types of polycythemia

The plasma level of tissue plasminogen activator antigen (t-PA-Ag) was examined in 86 patients with polycythemia (29 polycythemia vera, 11 secondary polycythemia and 46 with spurious polycythemia) and 24 healthy volunteers. Tissue plasminogen activator antigen was significantly decreased in patients with polycythemia vera in comparison with healthy controls. On the other hand, in patients with spurious polycythemia and secondary polycythemia t-PA-Ag concentration was significantly increased. There was no significant difference in t-PA-Ag levels in polycythemic patients with or without thromboembolic disease. A significant correlation was detected between t-PA-Ag level and hemoglobin or hematocrit concentration in patients with polycythemia vera (p = 0.02, r = 0.43). However, in patients with secondary polycythemia and spurious polycythemia, no significant correlation between t-PA-Ag and hemoglobin level was found. Plasminogen activator inhibitor (PAI) levels in patients with polycythemia vera and healthy volunteers did not differ significantly.     

Serum erythropoietin (EST) titers in anemia

Erythropoietin (ESF) titers were determined in sera from patients with different types of anemia using the fetal mouse liver cell bioassay. An inverse relationship was found between hemoglobin concentration and ESF titer. However, ESF titers differed markedly between patients at comparable degrees of anemia. Several groups of patients were distinguished on the basis of the activity of their erythroid bone marrow. In each of these groups, a significant negative correlation was found between the hemoglobin concentration and the logarithm of the ESF titer. ESF titers in patients with pure red cell aplasia were fourfold higher than those in patients with iron-deficiency anemia and tenfold higher than those in patients with megaloblastic anemia and homozygous sickle cell anemia at comparable hemoglobin concentrations. Following the initiation of specific therapy in patients with pernicious anemia and patients wit iron-deficiency anemia, serum ESF titers were found to decrease prior to any substantial rise in hemoglobin concentrations. In the patients with pernicious anemia, the lowest ESF levels were found 1 day after administration of vitamin B12, whereas in the patients with iron-deficiency anemia, the lowest ESF levels were reached in the second week of oral iron therapy. ON the basis of these data it was concluded that serum ESF titers in anemic patients are not only inversely related to the hemoglobin concentration but also to the activity of the erythroid bone marrow.     

Pure erythrocytosis classified according to erythropoietin titers

Erythropoietin titers, measured by bioassay of plasma extracts in hypertransfused mice, were determined in 162 patients with absolute erythrocytosis, and the results were correlated with the clinical diagnosis. Fifty-two patients met the diagnostic criteria for polycythemia vera, and all had low or nonmeasurable erythropoietin titers. Of the remaining 110 patients, 62 were suspected clinically as having secondary polycythemia. However, 15 had low erythropoietin titers, casting doubt on the accuracy of the clinical diagnosis. The pathogenesis of the erythrocytosis in the last 48 patients was unknown, and they were designated clinically as having pure erythrocytosis. However, in 20, the erythropoietin titers were increased, and in 28, the titers were low, suggesting that they belonged to at least two different groups. Using erythropoietin titers in the classification of absolute erythrocytosis, the first group should be added to the category of patients with secondary polycythemia as a subgroup with disease due to idiopathic overproduction of erythropoietin (hypererythropoietinemia or essential erythrocytosis). The second group should be added as a subgroup of patients with primary polycythemia under the term erythremia.     

An unusual case of toe ulceration

We describe an unusual presentation of toe ulceration in a 39-year-old otherwise healthy man. The left fifth toe was painful for several months with ulceration at the tip. The other toes appeared cyanotic and discolored. Foot pulses were normal. Laboratory testing revealed the platelet count at 1208 thousand/microliter, with hemoglobin 19.2g/dl and hematocrit 57%. The erythropoietin level was found to be markedly decreased at 1 mU/ml. The patient was given the diagnosis of polycythemia vera with iron deficiency. Phlebotomy was performed and aspirin and cytoreductive therapy with hydroxyurea was prescribed with resolution of the toe ulceration.     

Molecular basis for polycythemia

This overview concentrates on familial and congenital polycythemias in the context of other polycythemic disorders, with emphasis on those with established molecular lesions. Recent advances in the regulation of erythropoiesis, as they may relate to polycythemic states, are discussed as a background for those well-defined polycythemic states wherein the molecular defect has not yet been elucidated. Primary familial congenital polycythemias and congenital and familial secondary polycythemias, including hemoglobin mutants, methemoglobinemias and congenital 2,3-bisphosphoglycerate deficiency, are discussed. The most common primary polycythemia, polycythemia vera, as well as the only likely endemic congenital secondary polycythemia, known as Chuvash polycythemia, are discussed.     

Oxymetholone treatment in myelofibrosis

Summary In order to study the effect of oxymetholone therapy in advanced myelofibrosis, 11 patients (4 females, 7 males) were given, 3–5 mg per kg body weight, long-term oxymetholone treatment in a prospective multicenter study. Five cases had previously had a diagnosis of polycythemia vera. All patients had anemia initially, 4 leukocytopenia and 10 thrombocytopenia in addition. Hepato-splenomegaly was present in all cases but in varying degree. Five patients required regular blood transfusions before treatment.In 9 of the 15 courses given, there was normalization of the peripheral blood or substantial improvement (better than 3 g hemoglobin/dl or 50×10⁹ platelets/1) after androgens. Significant effects were noted both on hemoglobin values and platelet counts. The need for blood transfusions ceased completely in all 5 cases. When oxymetholone treatment was reduced or interrupted 4 patients relapsed; 2 of them responded to a renewed course. The red cell counts returned to previous polycythemic values in one patient and another died from acute leukemia.The results of this study suggest that androgens might be of value in advanced cases of myelofibrosis with transfusion-requiring anemia or severe thrombocytopenia.Supported by Lotten Bohman Fund and Astra-Syntex AB     

Thrombocytosis in young people: Evaluation of 57 cases diagnosed before the age of 40

Summary Over the past 13 years 57 cases of primary thrombocytosis in young people have been studied. Only patients with a platelet count over 500×10⁹/liter and a follow-up longer than 2 years were considered. Thrombocytosis in young people represents approximately 25% of total cases referred to our department during this period. The most common causes are essential thrombocythemia (20 cases) and secondary thrombocytosis (22 cases). The highest platelet counts are found in essential thrombocythemia patients. Most of our patients were discovered by a fortuitous hematological examination. In contrast, 5 out of the polycythemic patients were recognized after a thrombosis. The same was true for 2 out of 20 essential thrombocythemia subjects. Four subjects (2 essential thrombocythemia and 2 secondary thrombocytosis) were diagnosed after hemorrhages. The overall survival was very good except for leukemic patients and thrombocytosis secondary to neoplasms. Vascular complications after diagnosis were scarce: 2 polycythemia vera patients showed bleedings during antiaggregating therapy. None of our patients developed epithelial cancer, malignant lymphoma or myelofibrosis. Vascular traumata seem more frequent in polycythemia vera regardless of age. Therefore, it seems useful to treat polycythemic patients, while no therapy seems to be indicated in other forms of thrombocytosis.This study was supported in part by grants from M.P.I., Rome (grant 1592/1988) and from the Veneto Regional Government, Venice, Italy     

Polycythemia as the first manifestation of Cushing's disease

A 39-yr-old man presented to our hospital with unexplained erythrocytosis and hypertension. His follow-up for erythrocytosis had begun 2 yr earlier in another hospital and he had been diagnosed with polycythemia rubra vera. On admission to our hospital he was hypertensive (165/95 mmHg) and, except for the presence of moon-like face and facial plethora, his physical examination was normal. His hemoglobin concentration was 19.2 g/dl, and hematocrit was 58.9% with an increased red blood cell mass of 58 ml/kg as measured by radioisotope (Cr51). Blood film, other hematological indices except for elevated leukocyte alkaline phosphatase score, arterial gas analysis, and examination of aspirated bone marrow were all normal. An abdominal ultrasonography showed no evidence of splenomegaly. A diagnosis of probable secondary erythrocytosis was made. Early-morning serum cortisol and 24-h urinary free cortisol concentration as well as serum ACTH were high. Serum cortisol was not suppressed by low-dose dexamethasone, but suppressed by high-dose dexamethasone. Pituitary magnetic resonance imaging showed no lesion. After inferior petrosal sinus sampling suggesting right-central ACTH secretion, the patient underwent transnasal-transsphenoidal pituitary adenomectomy. Both hypercortisolemia and erythrocytosis regressed completely after the adenomectomy. After the operation, the patient's hemoglobin concentration and hematocrit decreased steadily, and 1 month post-adenomectomy his hemoglobin is 14.9 g/dl and hematocrit 44.8%. Thus, Cushing's syndrome should be a routine part of evaluation of unexplained polycythemia.     

Serum Erythropoietin Levels by Radioimmunoassay in Polycythaemia

A radioimmunoassay (RIA) method for erythropoietin (Epo) was developed and validated against the polycythaemic mouse assay. The correlation was good, with a r = 0.94. Several other criteria of specificity were also filled by the RIA, which had a lower detection limit of 5 mU/ml. The mean serum-Epo level in 6 patients with secondary polycythaemia, 50.2 + 26.2 mU/ml, was significantly higher than in a group of 11 normal subjects, 28.7 + 7.2 mU/ml (P < 0.0002). However, the Epo level in 31 polycythaemia vera (PV) patients, M = 21.9 + 6.6 mU/ml, was not significantly different from normal (P = 0.006). Since previous studies with bioassay of heat-treated and concentrated plasma samples have shown a decreased serum-Epo level in PV, Epo levels were measured before and after heat treatment and concentration of samples from normals and polycythaemics. It was found that the levels of immunoreactive material increased after heat treatment and 40 times concentration in samples from normals and patients with secondary polycythaemias, but decreased in PV. We conclude that the Epo levels in serum in the low range measured by our and previous RIA:s probably are not true Epo levels but are partly due to an unspecific serum effect, that was removed by heat treatment.     

Clinical characteristics of polycythemia vera in the elderly]

Of 43 elderly patients who were suspected to have polycythemia between October 1990 and July 1998, 12 patients showed an increased red cell volume measured by 51Cr-labeled red blood cells. We analyzed the clinical characteristics of the 12 patients consisted of 7 men and 5 women, with a median age of 71 (range: 57-92). Chief complaints were headaches and dizziness (3 cases), symptoms of other conditions than polycythemia (4 cases). Five patients had no symptoms. Five of 6 patients over 70 years old had no symptoms due to polycythemia. Seven cases (58%) showed splenomegaly and three cases (25%) showed hepatomegaly. Laboratory findings were as follows: WBC 9.7 +/- 3.9 x 10(3)/microliter (mean +/- SD, p < 0.02 vs normal control), Hb 17.9 +/- 4.2 g/dl (p < 0.001), Plt 39.7 +/- 26.0 x 10(4)/microliter, EPO 13.8 +/- 5.2 mU/ml (p < 0.0001), NAP score 258 +/- 114, Vit. B12 1,686 +/- 2,156 pg/ml, arterial O2 saturation more than 92% in all cases. The diagnosis of all cases was polycythemia vera according to the diagnostic criteria of Polycythemia Vera Study Group. Associated conditions included 8 cases of thrombosis (cerebral thrombosis 4, thrombophrebitis 2, myocardial infarction 1, ischemic colitis 1) and 3 cases of malignancy (esophageal cancer 1, breast cancer 1, renal cancer 1), none of which was therapy-related cancer. Six patients (50%) had only phlebotomy, three (25%) only chemotherapy, and three (25%) both phlebotomy and chemotherapy. Patients over 80 years old needed neither intensive nor continuous treatment. Only one patient died due to esophageal cancer at age 89.     

Hemoglobin Kansas found in a patient with polycythemia

Summary A 62-year-old woman, long suspected of having heart disease, was admitted to our hospital for thorough examination. Her hemoglobin level was 17.7 g/dl and her 2.3-DPG level was 8.90 M/ml RBC. The patient proved to have polycythemia, hemoglobin Kansas, and diabetes mellitus. To our knowledge, this is the third case of hemoglobin Kansas in the world.     

Polycythemia vera and other primary polycythemias

PURPOSE OF REVIEW: Diagnosis and therapy of polycythemia vera are controversial since the molecular basis of polycythemia vera remains unknown. Distinguishing between polycythemia vera and other polycythemic disorders can be very challenging. The purpose of this review is to discuss the recent progress in this area and critically review the published data in context of our knowledge of other polycythemic disorders. RECENT FINDINGS: Erythropoietin is the principal regulator of regulator of erythropoiesis; its production is regulated by the degree of hypoxia. Our knowledge of cellular responses to hypoxia has recently exploded and led to the elucidation of the molecular basis of a polycythemia caused by augmentation of hypoxic sensing, Chuvash polycythemia. Similar progress in understanding the molecular basis of polycythemia vera has been elusive. A simple, readily available laboratory test to establish a diagnosis of polycythemia vera would be highly desirable; however, none exists. The value of quantization of neutrophil PRV-1 mRNA, platelet c-mpl expression, in vitro assays of erythroid progenitor cells, serum erythropoietin levels, establishing clonality in female subjects using assays employing X-chromosome-based polymorphism assays, and the progress in the chromosomal location of the gene is discussed. Integration of this information underlies the complexity of the molecular biology of polycythemia vera and indicates likely interaction of multiple genetic events in the genesis of polycythemia vera. SUMMARY: The existence of family clustering of PV may facilitate the search for PV molecular basis. Only collaborative interaction of clinical researchers and laboratory scientists will lead to meaningful progress in determining the molecular basis of PV.     

Atrial natriuretic peptide in relative polycythemia and polycythemia vera

Atrial natriuretic peptide (ANP) levels have been tested in patients with chronic relative polycythemia (RP), polycythemia vera, and in healthy subjects in order to find a possible underlying pathophysiological mechanism for relative polycythemia. No difference in statistical significance has been found between the mean atrial natriuretic peptide levels of the polycythemic patients and the control group. It is suggested that ANP probably plays no significant role in the contraction of plasma volume observed in normotensive patients with RP.     

Assessment of an EIA for measuring human serum erythropoietin as compared with RIA and an in-vitro bioassay.

A recently developed enzyme-linked immunosorbent assay (EIAZ, ELISA) using two murine monoclonal anti-erythropoietin antibodies was compared with a radioimmunoassay (RIA) and a commercial in-vitro bioassay, EPOS, for measuring serum erythropoietin (Epo) in humans. Specificity and validity for Epo-EIA and the other two assays were examined. The serum Epo in normal subjects was 18 +/- 12 mU/ml (mean +/- SD, n = 80) for EIA compared with 22.5 +/- 18.5 mU/ml (n = 20) for RIA and 136 +/- 132 mU/ml (n = 14) for the bioassay. The serum Epo concentrations in normals and patients were highly comparable between EIA and RIA for Epo (P less than 0.01, r = 0.95). Epo concentrations by the EIA for normal female and male subjects were 20.5 +/- 13 and 16.5 +/- 10 mU/ml, respectively. Epo levels in patients with secondary polycythaemia or autoimmune haemolytic anaemia were significantly higher than normal subjects by the three methods. Epo levels in patients with chronic renal failure were within the normal range. By the EPOS bioassay, the Epo concentrations of normals and patients with renal failure were significantly higher than expected (136 +/- 132 and 447 +/- 273, respectively). Due to its inherent design, the EPOS bioassay possibly measures bone marrow proliferative activity in response to other serum growth regulators besides erythropoietin and was found to be unsuitable for clinical assessment of Epo. We concluded that the new EIA and RIA were similarly sensitive, reliable and accurate for measurement of serum Epo. The EIA method has the advantage of being less time consuming, more convenient and avoids the use of a radioisotope.     

EVIDENCE FOR IMPAIRED ERYTHROPOIETIN RESPONSE TO ANAEMIA IN RHEUMATOID DISEASE

In this study we determined the serum erythropoietin (Epo) levelsof 97 anaemic rheumatoid (RD) patients (Hb< 11 g/dl) of whom44 had serum ferritin >60 µg/l (anaemia of chronicdisorders; ACD), 26 had ferritin 20–60 µg/l and27 had ferritin <20 µg/l. These results were comparedwith the Epo levels of 36 iron deficient controls (Hb<11g/dl), 33 non-anaemic RD patients and 33 normals. The serumEpo levels of anaemic subjects were significantly higher (P<0.05)than those of non-anaemic patients. Despite similar Hb, theEpo results (geometric mean (confidence limits)) of the ACDgroup (38 (32,45) mU/ml) and of RD patients with ferritin of20/60 .µg/l (39 (33,46)mU/ml) were significantly lower(P<0.05) than those of iron deficient controls (65 (52,80)mU/ml).When the Hb fell to 10 g/dl or less, the serum Epo of 13 RDpatients with ferritin <20 µg/l was 65 (47,89)mU/ml,significantly lower (P<0.05) than that of 17 iron deficientcontrols (104 (78,136)mU/ml). These results justify clinicaltrials of recombinant human Epo in RD patients with ACD. KEY WORDS: Haemoglobin, Serum ferritin, Serum erythropoietin     

Phlebotomy improves pulmonary gas exchange in chronic mountain polycythemia

There is not unanimous agreement in the literature regarding the effects of bleeding on pulmonary gas exchange in polycythemic patients. Spirometry, alveolar arterial O2 and CO2 tension differences, PaO2 breathing 100% oxygen and carbon monoxide-diffusing capacity were measured before and after 1 week of chronic phlebotomy in 4 chronic mountain polycythemic patients. Studies were carried out at 3,700 m above sea level (PB = 491 mm Hg). Before phlebotomy, 2 patients showed abnormal spirometry and gas exchange. Only 1 patient had high PaCO2 and all of them showed low values of PaO2 breathing oxygen. Phlebotomy improved both spirometry and gas exchange. Improvement in arterial oxygen saturation and PaO2 could not be attributed to changes in alveolar ventilation, but rather to better distribution of VA/Qc ratios since physiological dead space decreased. Our results are similar to those reported in polycythemia vera patients. A significant correlation between the changes in PaO2 with phlebotomy and the control PaO2 have been found from 45 polycythemic patients with chronic obstructive pulmonary disease collected from the literature. It is concluded that excessive polycythemia worsened hypoxemia and that phlebotomy improved gas exchange.     

Erythropoiesis-inhibiting factor(s) (EIF): methodologic studies.

Erythropoiesis-inhibiting factors (EIF) have been demonstrated in plasma from hypertransfused animals and from polycythemic individuals during periods of hyperoxia, but there is a decided discrepancy in the data published. In the present paper methodologic variations of a bioassay for demonstrating the erythropoiesis-inhibiting factor are discussed. In these studies no inhibitor of erythropoiesis could be demonstrated in plasma from hypoxia-induced polycythemic mice (HPM) on posthypoxic day 5. Injections of RBC or an equal amount of hemolyzed RBC were capable of suppressing the stimulatory effects of ESF, indicating that a red cell constituent may be responsible for the inhibitory effect observed. Transfusion-induced polycythemic mice (TPM) were therefore considered to be less suitable for demonstrating erythropoiesis inhibitors. Our results from testing several doses of a urinary EIF in normal mice, TPM and HPM, indicated that the HPM provided the most sensitive assay system. A similar effect was obtained with hypoxia-induced polycythemic rats. The most marked effect was seen in HPM when the EIF was injected shortly before administering the ESF, while the effect was less pronounced when the EIF was injected 24 hr before or after the ESF.     

Remarkable improvement of anemia by administration of recombinant human erythropoietin in a patient with aplastic anemia

A 69-year-old female was admitted for pancytopenia. The hematological examination showed leukocytes 1,800/microliters, hemoglobin 5.3 g/dl and platelets 9.6 x 10(4)/microliters. A bone marrow aspiration revealed hypoplasia, but no abnormal cells. Serum erythropoietin titer was 5,100 mU/ml. Diagnosis of aplastic anemia was made. She received 400 ml of blood transfusion twice, and was then treated with recombinant human erythropoietin (rHuEPO) (12,000 U/day) three times a week for eight weeks. Hemoglobin level gradually increased to the level of 12.0 g/dl. This case suggests that there are some cases of aplastic anemia which can respond to treatment with rHuEPO.     

Quantitation of erythropoietin stimulatory activity using [3H]thymidine uptake by K562 cells

A microassay for erythropoietin (Ep) activity in serum using [3H]thymidine uptake by K562 cells is presented. The method is similar to that of Krystal except that cells of the K562 human pluripotent leukemia cell line replace spleen cells from phenylhydrazine-treated anemic mice. Response to the hormone by K562 cells and spleen cells was colinear. Using the Krystal bioassay, 14 young hemoglobin S homozygotes had Ep activity levels of 17.9-113.8 mU/ml serum, whereas the new method with K562 cells gave a range of 19.2-115.3 mU/ml. The correlation coefficient between the two sets of data (r) was 0.999 (p less than 0.001). With the modified technique we have assayed 34 sickle cell patients, whose sera ranged from 19.2 to 1400 mU of Ep/ml with corresponding hemoglobin concentrations of 10.7 g % to 3.0 g %. Values for normal subjects were 22.1 +/- 2.1 mU/ml (n = 7). The stimulation of [3H]thymidine uptake is significantly inhibited by an anti-Ep antiserum. The assay permits quantification of stimulatory activities in a large number of samples with relative ease and is also suitable to explore the interactions of erythropoietic factors with their appropriate receptors on stem cells.