Case Report: Clinical and Pharmacokinetic Profile of Lithium Monotherapy in Exclusive Breastfeeding. A Follow-Up Case Series

High lithium concentration at delivery is a potential risk factor for adverse outcomes in breastfed infants: a retrospective cohort study

BACKGROUND

Neonatal effects of late intrauterine and early postpartum exposure to lithium through mother's own milk are scarcely studied. It is unclear whether described symptoms in breastfed neonates are caused by placental lithium transfer or postnatal exposure to lithium through breastfeeding. We aimed to investigate lithium clearance and neonatal morbidity in breastfed infants with high versus low serum lithium concentrations at birth.

METHODS

This retrospective study focused on breastfed infants to women treated with lithium during and after pregnancy, born between 2006 and 2021 in Stockholm, Sweden. Information on serum lithium concentrations and adverse neonatal outcomes was obtained from medical records. Neonatal symptoms and lithium clearance were compared between a high exposure group (HEG, lithium concentrations ≥ 0.6 meq/l) and a low exposure group (LEG, < 0.6 meq/l).

RESULTS

A total of 25 infant-mother dyads were included. Median lithium serum concentration at birth was 0.90 meq/l in the HEG as compared with 0.40 meq/l in the LEG (p < 0.05). The difference was still significant at follow-up (0.20 meq/l vs 0.06 meq/l, p < 0.05), despite reduction in maternal dose. The rate of neonatal symptoms was 85.7% in HEG and 41.2% in LEG (p = 0.08) at birth and 28.6% vs 11.8% at follow-up (p = 0.55). Furthermore, 28.6% of infants in HEG were admitted to neonatal care, vs 5.9% in LEG (p = 0.19). Two infants in the HEG had therapeutic lithium levels at follow-up. All infants with symptoms at follow-up were either in the HEG or exposed to additional psychotropic medication.

CONCLUSIONS

Neonatal symptoms are common after late intrauterine lithium exposure, however transient, treatable and mostly mild. In this study, a high lithium concentration at birth was a risk factor for an increased lithium level at follow-up. Polypharmacy may constitute an additional risk factor. This study suggests that the late intrauterine exposure to lithium might add to the adverse effects in lithium-exposed, breastfed infants. Consequently we recommend breastfed infants with therapeutic lithium concentrations at birth to be followed up promptly to avoid lithium toxicity.

BMP/Smad Pathway Is Involved in Lithium Carbonate-Induced Neural-Tube Defects in Mice and Neural Stem Cells

Neural-tube defects (NTDs) are one type of the most serious birth defects. Studies have shown that inositol deficiency is closely related to the occurrence of NTDs. Bone morphogenetic protein (BMP)-mediated Smad signaling pathways have been implicated in neurogenesis and neural-tube closure. However, the role of the BMP/Smad pathway in inositol-deficiency-induced NTDs remains unclear. Inositol-deficiency models in C57 mice and mouse neural stem cells (mNSCs) were induced with Li₂CO₃ treatment or inositol withdrawal. The role of the BMP/Smad pathway in the regulation of cell proliferation and the development of NTDs was determined utilizing qRT-PCR, HE staining, Western blot, immunostaining, MTT assay, EdU staining, and flow cytometry. The intraperitoneal injection of Li₂CO₃ at Embryonic Day 7.5 induced the occurrence of NTDs. The mRNA levels of Bmp2, Bmp4, Smad1, Smad5, Smad8 and Runx2, the phosphorylation of Smad1/5/8, and the nuclear translocation of Runx2 were significantly increased in NTD embryonic brain tissues and mNSCs exposed to Li₂CO₃ or an inositol-free medium, which were suppressed by BMP receptor selective inhibitor LDN-193189. The Li₂CO₃-induced phosphorylation of Smad1/5/8 was inhibited by inositol supplementation. Cell proliferation was significantly promoted by Li₂CO₃ exposure or the absence of inositol in mNSCs, which was reversed by LDN-193189. These results suggest that the activation of the BMP/Smad signaling pathway might play an important role in the development of NTDs induced by maternal Li₂CO₃ exposure via inositol deficiency.

Early Postnatal Outcome and Care after in Utero Exposure to Lithium: A Single Center Analysis of a Belgian Tertiary University Hospital

Knowledge of the impact of in utero exposure to lithium during the postnatal period is limited. Besides a possible teratogenic effect during the first trimester, exposure during the second and third trimesters might lead to neonatal effects. Uniform guidelines for postnatal management of these neonates are lacking. The aim was to retrospectively describe all neonates admitted to the University Hospitals Leuven after in utero exposure to lithium (January 2010 to April 2020), and to propose a postnatal care protocol. Descriptive statistics were performed. For continuous parameters with serial measurements, median population values were calculated. In total, 10 mother-neonate pairs were included. The median gestational age was 37 (interquartile range, IQR, 36-39) weeks. Neonatal plasma lithium concentration at birth was 0.65 (IQR 0.56-0.83) mmol/L with a median neonate/mother ratio of 1.02 (IQR 0.87-1.08). Three neonates needed respiratory support, 7/10 started full enteral (formula) feeding on day 1. The median length of neonatal stay was 8.5 (IQR 8-12) days. One neonate developed nephrogenic diabetes insipidus. This study reported in detail the postnatal characteristics and short-term neonatal outcomes. A postnatal care protocol was proposed, to enhance the quality of care for future neonates, and to guide parental counselling. Future prospective protocol evaluation is needed.

Lithium use during breastfeeding was safe in healthy full-term infants under strict monitoring

AIM

Previous studies on breastfeeding during lithium therapy have shown conflicting results. The aim of this study was to evaluate the safety when practising thorough follow-up of the infants.

METHOD

This retrospective study focused on women with lithium medication, and their breastfed infants born between 2006 and 2021 in Stockholm, Sweden. Information about infant serum lithium concentrations and clinical status was collected from medical records.

RESULTS

In total, 30 infants exposed to lithium through breastmilk, 21 girls and 9 boys, were included. The median age at follow-up was 40 days (range 8-364 days). The median lithium serum concentration was 0.10 mmol/L in the second week of life (range <0.05-0.7 mmol/L), 0.08 in week 2-4 (range <0.05-1.2), 0.06 in the second month of life (range <0.05-0.2) and 0.07 after 2 months of age (range <0.05-0.2). Unexpectedly high lithium concentrations were found in two infants in the first month of life. Apart from poor weight gain, no adverse effects were found.

CONCLUSION

Serum lithium concentrations in breastfed infants were stabilised at barely measurable levels after the first weeks of life. Before that, concentrations higher than the mothers were found. Lithium treatment during breastfeeding can be considered safe under strict follow-up.

Neonatal Feeding Trajectories in Mothers With Bipolar Disorder Taking Lithium: Pharmacokinetic Data

Purpose: Women who take lithium during pregnancy and continue after delivery may choose to breastfeed, formula feed, or mix these options. The aim of the study was to evaluate the neonatal lithium serum concentrations based on these three feeding trajectories. Methods: We followed 24 women with bipolar disorder treated with lithium monotherapy during late pregnancy and postpartum (8 per trajectory). Lithium serum concentrations were determined by an AVL 9180 electrolyte analyser with a 0.10 mEq/L detection limit and a 0.20 mEq/L limit of quantification (LoQ). Results: There was complete lithium placental passage at delivery, with a mean ratio of lithium concentration in the umbilical cord to maternal serum of 1.12 ± 0.17. The median times to LoQ were 6-8, 7-8, and 53-60 days for formula, mixed, and exclusive breastfeeding respectively. The generalized log-rank testing indicated that the median times to LoQ differ according to feeding trajectory (p = 0.037). According to the multivariate analysis-adjusted lithium serum concentrations at birth, times to LoQ are, on average, longer under exclusive breastfeeding (formula, p = 0.015; mixed, p = 0.012). No lithium accumulation was observed in infants under either exclusive or mixed breastfeeding. During the lactation follow-up, there was no acute growth or developmental delays in any neonate or infant. Indeed, lithium concentrations in the three trajectories declined in all cases. However, the time needed to reach the LoQ was much longer for those breastfeeding exclusively. Conclusions: In breastfeed infant no sustained accumulation of lithium and no adverse effects on development or growth were observed.