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Is there poison in our Parenteral Nutrition Solutions?
X Simpósio Internacional de Neonatologia
Rio de Janeiro, Brasil
June 23, 2016
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“All the good questions have already been answered”
Quote from a former fellow
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Introduction: Parenteral Nutrition
• Modern parenteral nutritional formulations were developed in the late 1960’s.
– > 40,000 patients in the US are permanently dependent on parenteral nutrition to survive
– Many more are sustained for finite periods of time on complex intravenous nutritional formulas
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Trace Minerals
• Until 30 years ago, trace elements were thought to be of little significance in human nutrition.
• It is now recognized that many factors can render individuals and population groups susceptible to disease resulting from trace element deficiencies or excess.
Essential Trace Metals
Eight trace metals are
nutritionally essential
for humans.
Quantitatively a small fraction of the total
mineral content of the human body
Play an important role in numerous metabolic
pathways
Zn
30
Se
34
Cr
24
Mo
42
Mn
25
I
53
Fe
26
Cu
29
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Trace Minerals • All nutrients have an optimal range of intake, with either
deficiency or excess being potentially harmful
• Trace elements of toxic importance only: aluminum and mercury
• Trace elements with limited evidence for human deficiencies: manganese and molybdenum
• Clinical deficiencies have been described for 6 of the elements: iron, iodine, zinc, copper, chromium, and selenium – Preterm infants are at increased risk of developing trace element
deficiencies • Low stores at birth (accretion takes place in 3rd trimester)
• Rapid postnatal growth increase demands
• Variable intake
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Infant Nutrition Human Milk: The Gold Standard
The trace element content in human milk is the accepted “gold standard” for nutrient intake in the full term infant.
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There is no “Gold Standard” for the Preterm Infant
Acceptable objectives:
– Prevent trace mineral deficiencies
– Accretion of stores equivalent to that of developing fetus
– Avoidance of toxicity from excess intake
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Zinc
• Best studied of the trace metals
• Nutritionally essential
– Maintenance of cell growth and development
– Over 200 Zn metalloenzymes associated with CHO and energy metabolism, protein catabolism, nucleic acid synthesis, heme biosynthesis and gene transcription
– Content of Zn in colostrum is high but decreases postnatally. Variable content in preterm human milk • Frank Zn deficiency has been described in breast fed preterm
infants
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Zinc Deficiency
Clinical effects
o Skin lesions
o Growth failure
o Poor wound healing
o Hair loss
o Diarrhea
o Decreased protein synthesis
o Depressed immune function
o Common in preterm infants receiving TPN in the 1970s
o Subclinical zinc deficiency in premature infants fed human milk
o Current recommendations for PN: 400 μg/kg/d
Acrodermatitis enteropathica
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Recognition of zinc deficiency in premature infants led to the formulation and marketing of essential trace metal
“cocktails” for patients receiving PN
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Trace Element Supplementation in TPN
Trace Element per 1 ml Recommended
Daily Dose
Zinc 1500 µg 150 µg/kg, <14 d
400 µg/kg, >14 d
Copper 100 µg 20 µg/kg
Manganese 25 µg 1 µg/kg
Chromium 0.85 µg 0.14 - 0.2 µg/kg
(Selenium, a trace element not included in Multitrace®-4
Neonatal, is added individually to PN solutions.)
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Manganese
• An essential mineral required for normal growth and development
• Exposure to high [Mn] results in manganism – clinically resembles Parkinson’s disease
– occurs under unique environmental exposure paradigms
– destructive symmetrical lesions in the basal ganglia, particularly in the globus pallidus, substantia nigra and subthalamic nucleus
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Mn Homeostasis
• Healthy adults are protected from Mn toxicity by three barriers
– the intestinal barrier adjusts Mn absorption based on dietary Mn content
– Normal hepatobiliary function- 90% of Mn is excreted in the bile
– the mature blood-brain-barrier
• In adults, despite large fluctuations in oral Mn intake, brain and other tissue Mn levels remain relatively constant
Britton and Cotzias 1966; Mahoney and Small 1968; Davis et al. 1993; Malecki et al. 1999;
Finley and Davis 1999; Dorman et al. 2000; Dorman et al. 2001
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Risk Factors for Mn Neurotoxicity: Parenteral Nutrition and Liver Disease • A Mn-containing trace element supplement is
typically added to PN solutions
– Fixed ratios of Zn, Cu, Cr, Mn
– Intravenous Mn bypasses the normal intestinal regulatory mechanisms
• Hepatic cholestasis is common in infants requiring prolonged PN
– Cholestatic liver disease is a known risk factor for Mn neurotoxicity • Biliary atresia
– Mn supplements should be withheld in patients with liver disease receiving PN
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Mn in Neonatal Nutrition Human
Milk
Cow Milk
Formula
Soy
Formula
PN
(No TES)
Multitrace®-4
Neonatal*
PN with TES
Mn Content
mg/L 3-10 30-50 180-300 7±1
2500
(0.2 ml/dL) 60
Absorption
(%) 8 2 <1 100 100 100
Trace element-supplemented PN provides >100 times
more Mn than would be absorbed by infants fed human milk
Human Milk Cow Milk Soy Formula PN PN+TE suppl
Mn
Ab
so
rpti
on
(m
g/k
g/d
)
0
2
4
6
8
10
0.06 0.1 0.5 1.0
8.5
(Based on 150 ml/kg/d)
Toxicity
in adults
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The Blood-Brain-Barrier
• Immature, more permeable BBB at a critical stage of brain development
• The neonatal rodent brain is more susceptible to the neurotoxic effects of manganese (Seth and Chandra, 1984;
Pappas et al. 1997; Dorman et al. 2000 )
• In monkeys and rats, a correlation exists between Mn brain concentrations and the severity of CNS symptoms (Suzuki et al. 1975; Roels et al. 1997)
• High dietary Mn intake in neonatal rats resulted in developmental deficits (Tran et al. 2002)
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Additional Considerations: Fe Deficiency
• Reciprocal relationship between Fe status and Mn brain uptake – In plasma, both metals are bound to albumin and transferrin
– Both are transported via transferrin-mediated endocytosis and the divalent metal transporter 1 (DMT-1)
Fe Conc. DMT-1 & TfR
Levels
Mn
Transport
Normal Normal Normal
High Low Decreased
Low High Increased
Aschner and Aschner 1990; Aschner and Aschner 1991; Erikson et al. 2002
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Mn Brain Deposition can be Assessed Non-invasively
• Mn is paramagnetic
• Detected by T1-weighted MRI
– Hyperintense signal -shortened T1 relaxation time (T1R) - in the basal ganglia
Adult receiving Mn-supplemented PN
(Kim et al. 2004)
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Parenteral Nutrition and Hypermanganesemia
• Manganese intoxication has been reported in association with PN solutions providing ~1.5-2.0 µg/kg/day for an average adult
– Elevated serum Mn levels
– Symmetrical high intensity T1-weighted MR signals in the globus pallidus
– Some patients had psychiatric symptoms and clinical signs of Mn-induced parkinsonism-like syndrome
– At particular risk are patients with cholestatic disease on long-term PN
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There are numerous case reports of abnormal T1-weighted MRIs in older
children and adults exposed to prolonged PN, but few prospective
studies in patients at any age
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Overall Goals of the Project
• Identify neonatal populations at increased risk of excessive brain Mn deposition and altered cognitive and motor development based on their
– dietary parenteral Mn intake
– degree of prematurity
– hepatic function
• Develop evidence-based recommendations for appropriate Mn supplementation and monitoring of infants receiving parenteral nutrition
Funding sources: NIEHS, the Gerber Foundation and the Vanderbilt CTSA
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Hypothesis
There is a direct association between shorter T1 relaxation time in the globus pallidus and
– Total dietary Mn
– Total days on PN
– Conjugated bilirubin levels
– Blood Mn concentrations
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MRI Methods
• Imaging: – Philips 1.5T Achieva scanner – IR Turbo Spin Echo acquisition – 0.7 x 0.7 x 4 mm voxels – 3:03 per scan (8 scans total)
• T1 relaxation time was estimated in each image voxel
• T1 map for each subject was aligned to a template brain
• Mean T1 measured in template ROI: Globus Pallidus
Inversion Time (s) S
ignal
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Methods
• Mn brain deposition by MR T1 relaxometry
• Mn in whole blood by HR-ICP-MS
• Extensive dietary logs with calculations of total, enteral and parenteral Mn from birth to date of MRI
• Statistical Methods: Multivariable linear regression to estimate the association between dietary Mn and T1R, controlling for GA and PMA at MRI
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Enrollment Criteria
NICU PN Group
• Greater than 30 days postnatal age
• In the preceding 4 weeks, received >75% of nutrition as PN
• Clinically stable for transport to MRI facility
MRI Control Group
• Clinically-indicated MRI
• Less than 2 weeks of PN
• No liver disease
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Study Population
High Exposure
N = 44
Motion artifact
N = 7
Severe lesions
N = 5
Died before MRI
N =1
Withdrew pre MRI
N = 2
MRI data available
N = 39
Low Exposure
N = 29
MRI data available
N = 19
Motion artifact
N = 7
Image axial
N= 3
Enrolled
N =73
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Study Population
Median (25th–75th quartile) NICU PN Group (N=39)
MRI Control Group (N=19)
GA (weeks)* 27 (25-35) 37 (35-39)
PMA at MRI (weeks) 40 (38-43) 39 (37-43)
Total days on PN prior to MRI* 48 (34-62) 2 (0-12)
Total Dietary Mn (birth to MRI) (ug)* 853 (669-1397) 96 (12-584)
Parenteral Mn (birth to MRI) (ug)*
415 (312–760) 5 (0–101)
Parenteral Mn (28 d before MRI) (ug)*
187 (102–407) 0 (0–67)
* P<0.001 Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Relationship Between Gestational Age and T1R
Globus Pallidus T1R is inversely related to GA (p<0.001) .
Gestational Age at Birth (weeks)
T1
Re
laxa
tio
n T
ime
(se
co
nds)
900
1000
1100
1200
1300
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GP Appears Bright in T1-weighted Images
Control NICU PN
T1R 1081 s T1R 1139 s
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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GP appears bright in T1-weighted images
Control Home TPN TPN
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Relationship between GP T1R and total dietary Mn After controlling for GA at birth, shorter T1 relaxation time was
associated with higher total manganese (P = 0.02)
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Relationship between GP T1R and parenteral Mn
After controlling for GA at birth, shorter T1 relaxation time was
associated with higher parenteral manganese (P = 0.02)
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Regression Models: Adjusted and Unadjusted Associations between Mn intake and GP T1R
Predictor: T1R Unadjusted (regression coefficients [95% CI]
Adjusted for GA (regression coefficients [95% CI]
Total Mn from birth -2.6 (-4.2, -0.29)* -3.3 (-4.4, -2.1)*
Parenteral Mn from birth -14 (-21, -7.5)* -14 (-20, -7.9)*
Total Mn (28d before MRI) -3.1 (-7, -0.7) -4.5 (-7, -2.1)*
Parenteral Mn (28 day before MRI) -24 (-36, -11)* -14 (-27, -1.6)*
Blood Mn (n=31) -2.4 (-7.9, 3) -1.8 (-5.6, 2)
* p< 0.05
The regression coefficients from multivariable regression models represent the unit
decrease in GP T1R for each 100-unit increase in the predictor.
For every 100-ug increase in parenteral Mn intake in the 28 d preceding the MRI, T1R
decreased by 14 ms (95% CI: -27, -1.6). This relation was maintained for parenteral Mn
exposure from birth to time of MRI. No significant association was observed between
T1R and enteral manganese intake. Similar or even stronger associations were observed
between Mn intake and putamen T1R.
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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Regression Models: Adjusted and Unadjusted Associations between Mn intake and GP T2R
Predictor Unadjusted (regression coefficients [95% CI]
Adjusted for GA (regression coefficients [95% CI]
Total Mn from birth -1.1 (-1.5, -0.6)* -1.6 (-2.9, 2-0.2)*
Parenteral Mn from birth -3 (-6.6, 0.6) -3 (-6.6, 0.6)
Total Mn (28d before MRI) -1.7 (-2.9, -0.4)* -1.6 (-2.9, -0.2)*
Parenteral Mn (28 day before MRI) 2.4 (-7.1, 12) 1.5 (-8.2, 11)
Blood Mn (n=31) 0.1 (-2, 2.2) 0.1 (-2, 2.1)
• p=0.05
The regression coefficients from multivariable regression models represent the
unit decrease in globus pallidus T2R for each 100-unit increase in the predictor.
An even weaker association was observed between Mn intake and putamen
T2R
Aschner JL et al. Am J Clin Nutr 2015;102:1–8
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• Four patients had toxic Mn levels (>30 mg/L).
• After controlling for GA at birth, whole blood Mn is not
associated with T1R in the GP or putamen, or with total
dietary, parenteral or enteral Mn.
Whole Blood Mn
Mn Concentration (mg/L) Median (IQR) Range
Whole Blood (Normal: 8-12) 13.2 (9.7–17.0) 3.5-56.6
PN (without trace elements) 7.6 (6.9–11.9) 6.9-11.9
PN (with trace elements) 60.0 (38.4–77.7) 38.4-77.7
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Impact of Hepatic Cholestasis
Conjugated bilirubin (mg/dL) Median (IQR) Range
Normal (<2) 2.7 (1.6–4.0) 0.1-27.9
Plots fix GA at 30 weeks and PMA at MRI at 39 weeks
Total Dietary Mn (mg)
• Higher conjugated bilirubin concentrations at the time of MRI magnified the
effects of parenteral Mn exposure such that every 100-mg increase in
parenteral Mn corresponded to a 17-ms decrease in T1R (95% CI: -23, -11).
• Conjugated bilirubin did not alter the relations between total manganese or
enteral Mn exposure and T1R to the same extent.
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Summary
• Dietary Mn exposure is inversely associated with GP T1R.
• T1 –weighted MRI can be used to screen infants on prolonged PN for increased brain Mn deposition.
• Hepatic cholestasis is a risk factor for increased brain Mn deposition in neonates receiving PN
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Hypotheses
Compared with unexposed age-matched controls, infants receiving prolonged Mn-supplemented PN will have
– lower Bayley III scores
– lower executive functioning index scores
– slower latencies and attenuated amplitudes on ERP testing
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Methods
Mn neurotoxicity: Serial assessments of • Neurodevelopmental exams at 6, 12 and 24 months
– Infanib, Bayley III
• Cognitive function at 12 months – Executive function testing
• Event-related potential (ERP) at NICU discharge, 6, and 12 months
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ERP TESTING Measures of cortical functioning (ERPs to speech sounds) recorded in the VCH NICU and/or the Follow-Up Clinic.
• 128-channel soft sensor array • 6 syllables x 25 trials • 10-15 min testing time
ERP
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After correcting for GA, higher dietary Mn was
associated with altered neural processing as
measured by
• differences in temporal ERP signal
amplitudes (p = 0.01)
• decreased cognitive, motor and
communication scores at 6 months of age
(p <0.01).
• decreased executive function at 12
months (p = 0.03).
Results: Neurodevelopment
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After correcting for GA at birth, ERP changes
correlated with globus pallidus MRI T1
relaxation time (p =0.01).
The length of PN was associated with
decreased neurodevelopmental scores at 12
months (p<0.01).
Results: Neurodevelopment
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Conclusions
• Current approach for trace element supplementation is not evidence based.
• Use of trace element solutions with fixed ratios limits flexibility needed to regulate Mn intake under various clinical conditions, such as liver disease or Fe-deficiency. –Only individualized supplementation will
achieve the appropriate intake
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Speculation
Some infants receiving prolonged PN are at risk for Mn neurotoxicity and associated developmental delays
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Acknowledgements
• The Gerber Foundation
• NIH/NIEHS (R21 ES013730)
• Vanderbilt GCRC (M01 RR 000095)
Vanderbilt Dept of Pediatrics Donna Daily, MD Nathalie Maitre, MD, PhD Michael Aschner, PhD Andres Martinez, MD Steven Steele, RN Amy Beller, RN, Amanda Mouvery NNP
Vanderbilt Center for Imaging Sciences Adam Anderson, PhD Christopher Gatenby, PhD
Vanderbilt Kennedy Center Julia Noland, PhD Alexandra Key, PhD
Vanderbilt Dept of Biostatistics J. Christopher Slaughter, PhD