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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