Does prematurity affect platelet indices?

Changes in Platelet Function in Preterm Newborns with Prematurity Related Morbidities

Platelet indices represent useful biomarkers to express the thromboembolic status, inflammatory response, and oxidative stress in preterm newborns. Our study presented platelet count and function changes in prematurity-related morbidities such as respiratory distress syndrome, intraventricular bleeding, and anemia of prematurity in preterm newborn cases reported to healthy full-term newborns by flow cytometry and hematological methods. The platelet volume represents the average size of platelets in the blood samples, showing the significantly increased values in preterm newborns compared with healthy full-term newborns due to increasing activated platelet production. Flow cytometric analysis of immature platelet fractions (IPF) made using thiazole orange staining to detect their mRNA content and a glycoprotein (anti-GPIIIa) antibody for platelet gating. CD61-TO expression from premature newborns was significantly lower compared to healthy full-term neonates. Preterm newborn cases with respiratory distress syndrome and a need for respiratory support (RDS+) were characterized by a significantly increased platelet volume and a decreased immature platelet fraction reported in RDS− cases. Evaluating the platelet function in the newborn is difficult because the laboratory methodologies work with small quantities of newborn blood samples. The immature platelet fractions and platelet volume promise to be diagnostic biomarkers for diseases.

Platelet Count and Volume and Pharmacological Closure with Paracetamol of Ductus Arteriosus in Preterm Infants

Background: Low platelet count might promote resistance to pharmacological closure with indomethacin and ibuprofen of a hemodynamically significant patent ductus arteriosus (hsPDA). However, no studies have investigated if this occurs with paracetamol. Methods: We retrospectively assessed the correlation between platelet count, mean platelet volume (MPV), and plateletcrit (PCT), as well as the effectiveness of paracetamol in closing hsPDA in infants born at 23⁺⁰–31⁺⁶ weeks of gestation who were treated with 15 mg/kg/6 h of i.v. paracetamol for 3 days. Results: We studied 79 infants: 37 (47%) Had closure after a course of paracetamol and 42 (53%) did not. Platelet count and PCT did not correlate with paracetamol success or failure in closing hsPDA, while MPV was lower at birth (10.7 ± 1.4 vs. 9.5 ± 1.1; p < 0.001) and prior to starting therapy (11.7 ± 1.9 vs. 11.0 ± 1.6; p = 0.079) in refractory infants. Regression analysis confirmed that the low MVP measured prior to starting the treatment increased the risk of hsPDA paracetamol closure failure (OR 1.664, 95% CI 1.153–2.401). Conclusions: The greater MPV correlated positively with the effectiveness of paracetamol in closing hsPDA, while platelet count and PCT did not influence closure rates. Additional studies are needed to confirm our results.

Perinatal factors affecting platelet parameters in late preterm and term neonates

Platelets parameters including platelet count (PLT), plateletcrit (PCT), mean platelet volume (MPV) and platelet distribution width (PDW) are associated with various physiological and pathological functions in various disease. However, few studies have addressed whether perinatal factors may be associated with platelet parameters at birth in a large cohort of late preterm and term neonates. The aim of this study to investigate perinatal factors affecting platelet parameters in late preterm and term neonates. We retrospectively investigated platelet parameters including PLT, PCT, MPV, and PDW on the first day of life in 142 late preterm and 258 term neonates admitted to our NICU from 2006 through 2020. PLT, MPV, PCT, PDW on Day 0 did not significantly differ between the two groups. In term neonates, multivariate analysis revealed that PCT correlated with being small for gestational age (SGA) (β = -0.168, P = 0.006), pregnancy induced hypertension (PIH) (β = -0.135, P = 0.026) and male sex (β = -0.185, P = 0.002). PLT was associated with SGA (β = -0.186, P = 0.002), PIH (β = -0.137, P = 0.024) and male sex (β = -0.166, P = 0.006). In late preterm neonates, multivariate analysis revealed that PLT were associated with PIH, whereas no factors associated with PDW and MPV were found. In all patients studied, chorioamnionitis (CAM) was significantly associated with MPV (CAM = 10.3 fL vs. no CAM = 9.7 fL, P<0.001). Multivariate analysis showed that SGA, male sex and PIH were associated with PCT and PLT. This study demonstrates that different maternal and neonatal complications affect platelet parameters in late preterm and term neonates.

Maturation of Platelet Function During Murine Fetal Development In Vivo

OBJECTIVE

Platelet function has been intensively studied in the adult organism. However, little is known about the function and hemostatic capacity of platelets in the developing fetus as suitable in vivo models are lacking.

APPROACH AND RESULTS

To examine fetal platelet function in vivo, we generated a fetal thrombosis model and investigated light/dye-induced thrombus formation by intravital microscopy throughout gestation. We observed that significantly less and unstable thrombi were formed at embryonic day (E) 13.5 compared with E17.5. Flow cytometry revealed significantly lower platelet counts in E13.5 versus E17.5 fetuses versus adult controls. In addition, fetal platelets demonstrated changed activation responses of surface adhesion molecules and reduced P-selectin content and mobilization. Interestingly, we also measured reduced levels of the integrin-activating proteins Kindlin-3, Talin-1, and Rap1 during fetal development. Consistently, fetal platelets demonstrated diminished spreading capacity compared with adults. Transfusion of adult platelets into the fetal circulation led to rapid platelet aggregate formation even in young fetuses. Yet, retrospective data analysis of a neonatal cohort demonstrated no correlation of platelet transfusion with closure of a persistent ductus arteriosus, a process reported to be platelet dependent.

CONCLUSIONS

Taken together, we demonstrate an ontogenetic regulation of platelet function in vivo with physiologically low platelet numbers and hyporeactivity early during fetal development shedding new light on hemostatic function during fetal life.

Is there a relationship between platelet parameters and patency of ductus arteriosus in preterm infants?

Postnatal closure of the ductus arteriosus is a complicated two-phase process involving functional and structural changes. So far, the precise mechanisms regulating this process are not fully understood. A growing body of evidence from recent studies suggests that platelets play a key role in inflammatory processes including ductal closure via interaction with endothelial cells. The aim of this study is to assess whether a relationship exists between the occurrence and/or closure of hemodynamically significant ductus arteriosus (HSDA) and platelet parameters (platelet count, circulating platelet mass, mean platelet volume, platelet distribution width) in preterm newborns. This single-center, retrospective study included 824 premature infants between 24 and 34 gestational weeks, evaluated by echocardiography at postnatal 72-96 h. Infants with and without HSDA (n = 208 vs. n = 616) were compared in terms of platelet parameters recorded within the first 3 days of life. Oral or intravenous ibuprofen was commenced for medical treatment, and echocardiography was repeated 24 h thereafter to determine ductal closure. No statistically significant difference could be demonstrated between the groups in terms of baseline platelet parameters. HSDA was independently associated with early-onset neonatal sepsis. Thrombocytopenia, low circulating platelet mass, high platelet distribution width, or high mean platelet volume could not be demonstrated as a risk factor for HSDA. None of the platelet parameters had an influence on ductal closure after medical treatment. Unlike most reports in the literature, presence of HSDA was not associated with any platelet parameter in our study. We could not demonstrate an association between any platelet parameter and either persistence or closure after medical treatment.

Platelet indices in neonatal sepsis: A review

Thrombocytopenia is a common hematological abnormality in neonates with sepsis. The autoanalyzers now-a-days readily provide platelet indices along with platelet counts without any additional cost. However these indices are not given proper weightage often. The important platelet indices available for clinical utility include mean platelet volume (MPV), platelet distribution width and plateletcrit that are related to morphology and proliferation kinetics of platelets. Studies in adult patients reported their role in the diagnosis of severe sepsis and prognosis of adverse clinical outcomes including mortality. Abnormal MPV can aid diagnosing the cause of thrombocytopenia. Low MPV associated with thrombocytopenia has been found to result in clinical bleeding. Other indices, however, are less studied. The studies addressing the importance of these platelet indices in neonatal sepsis are limited. The current review gives an overview of potential utility of important platelet indices in neonatal sepsis.

Platelet indices in late preterm newborns

BACKGROUND

The current study objective was to compare blood platelet indices in late preterm newborns (LPN) and full term newborns (FTN).

MATERIALS AND METHODS

We recruited 58 LPN and 71 FTN. Platelet indices were estimated in blood samples collected from the umbilical artery.

RESULTS

LPN demonstrated a decreased count of blood platelets (249 × 10³/μL) as compared to FTN (295 × 10³/μL), p < 0.001. Platelet hematocrit (PCT) also showed substantial differences in both groups (LPN = 0.2% vs. FTN = 0.23%; p < 0.001). Mean platelet volume (MPV) was found to be nearly the same (LPN = 7.98fl, FTN = 7.9fl). Platelet distribution width (PDW) was higher in LPN (52.8%) than in FTN (50.6%), p = 0.02. Large platelet count (LP) was lower in LPN (4.0%) in comparison with FTN (6.0%), (p = 0.01).

CONCLUSIONS

The obtained results may indicate immaturity of thrombopoiesis in newborns born late preterm. Decrease in platelet count, platelet hematocrit and large platelets can cause disturbances in the hemostatic system and lead to bleeding complications and can increase the risk of infections. Morphological parameters of blood platelets in infants born late preterm differ from those of term neonates as in other preterm infants. This reflects the immaturity of this newborn and shows the need to pay special diagnostic and therapeutic care to them.

Intraventricular Hemorrhage and Platelet Indices in Extremely Premature Neonates

Intraventricular hemorrhage (IVH) is a multifactorial disorder, the most important risk factors of which are prematurity and low birth weight. Disturbances in cerebral blood flow, inherent fragility of the germinal matrix vasculature, and platelet/coagulation disturbances are the 3 major pathogenic mechanisms. In this context, we investigated the role of platelet indices and several maternal and neonatal characteristics in the development of IVH through a retrospective cohort analysis of 130 extremely premature neonates, 24% of whom presented with severe IVH. There was a significant difference in platelet counts between the IVH and the control group on the first day of life (P=0.046). Presence of IVH was linked with lower birth weight (P=0.006) and lower gestational age (P=0.001). Platelet count on the first day of life was positively correlated with survival (P=0.001) and, along with platelet mass, was indicative of the worst IVH grade recorded for each neonate (P=0.002 and 0.007, respectively). Prolonged prothrombin time was also correlated with IVH (P<0.001), but factor analysis supported no prominent role. Maternal medications seem to play a minor role as well. In conclusion, IVH in extremely premature infants cannot be solely explained by platelet parameters, and further studies are required to determine the relationships between IVH, platelet indices, and outcomes.

Hemostatic profile in healthy premature neonates; does birth weight affect the coagulation profile?

Context:

There are limited studies assessing the neonatal hemostatic factors in relation to birth weight.

Aims:

This study aims to compare the coagulation factors between three groups of neonates with different birth weight for gestational age (GA).

Settings and Design:

In a cross-sectional study, 74 healthy premature neonates were involved.

Subjects and Methods:

Serum prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio (INR), thrombin clotting time (TT), and levels of fibrinogen, anti-thrombin III, protein S and protein C were measured. Neonates were classified into three groups according to birth weight, including small, appropriate and large for gestational age (SGA, AGA, and LGA).

Statistical Analysis Used:

Statistical analysis was performed using SPSS software.

Results:

There was a significant difference in the levels of protein S (P < 0.001), protein C (P = 0.004), and values of APTT (P = 0.01) between three groups. Other coagulation factors however, did not represent a significant pattern (P > 0.05). Protein S concentration, directly (B = 0.78, P < 0.001), and APTT, inversely (B = −0.29, P = 0.03), associated with birth weight after adjustment for GA and sex.

Conclusions:

Despite the decrease in APTT from SGA to AGA, and LGA neonates, levels of protein S increases directly with birth weight. However, no other coagulation factors revealed an explainable pattern in relation to the state of SGA, AGA, or LGA.

Platelet indices in SGA newborns

PURPOSE

The current study objective was to compare blood platelet indices in full-term small-for-gestational-age newborns (SGA) and full-term appropriate-for-gestational-age newborns (AGA).

MATERIALS/METHODS

We introduced to our study 61 SGA newborns (31 females and 30 males) and 70 eutrophic infants (32 females and 38 males). The SGA newborns were divided into two groups: those weighing less than the 5th centile: 35 infants (16 females and 19 males) and those between the 5th and 10th centiles: 26 infants (15 females and 11 males). Platelet indices were estimated in blood samples collected from the umbilical artery.

RESULTS

SGA demonstrated a decreased count of blood platelets (238×103/μ) as compared with AGA (286×103/μL), p=0.0001. Platelet hematocrit (PTC) also showed differences in both groups (SGA=0.19% vs. AGA=0.22%; p=0.0005). Mean platelet volume (MPV) was higher in SGA (8.25fl) as compared with AGA (7.84fl); p=0.008. Large platelet count (LPLT) was higher in AGA 6.26% vs. SGA=4.75%; p=0.01. Platelet distribution width (PDW) was found to be nearly the same (SGA=47%, AGA=46%). PDW was higher in SGA newborns < 5th centile (43%) as compared with SGA infants between the 5th and 10th centiles (52%); p=0.008.

CONCLUSIONS

A decreased blood platelet count, platelet hematocrit and large metabolically active platelet count, which in addition to reduced synthesis and excessive consumption of coagulation factors in states of hiperclotting is characteristic of IUGR, enhances the possibility of bleeding complications and increases the risk of infections. From a clinical point of view, it is important to take into consideration the degree of intrauterine hypotrophy during the evaluation of hemostatic disorders.