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PubMed This is a summary of 25 peer-reviewed journal articles Updated
Medical Genetics

Recognizing and Managing Metabolic Crises

At a Glance

For children with MCEE deficiency, infection, fever, fasting, or illness can trigger a metabolic crisis. Start the clinician-written sick-day plan early, contact the metabolic team, and seek emergency care for breathing trouble, seizures, severe drowsiness, or inability to keep fluids down.

While many children with MCEE deficiency have a mild course and may never experience a serious medical event, every family must be prepared for a metabolic crisis [1][2]. A crisis occurs when the body is under stress—usually from an infection, fever, or fasting—and begins to break down its own muscle and fat for energy. This process, called catabolism, causes a rapid buildup of metabolites that the body cannot clear [3][4].

Recognizing the Red Flags

A metabolic crisis is a medical emergency. Because symptoms can worsen quickly, you should seek immediate care if you notice any of the following “red flag” symptoms. Do not wait for laboratory results to take action. [5][6]

Immediate Emergency (Call 911 or Go to the ER)

Bring your Emergency Letter. Do not force oral fluids if your child is extremely drowsy, having a seizure, or cannot swallow safely due to the risk of choking.

  • Altered Consciousness: Your child is unusually sleepy, very difficult to wake up, or seems confused or “out of it” (encephalopathy) [5][7].
  • Respiratory Distress: Rapid, shallow, or heavy breathing (this may be the body’s attempt to blow off excess acid) [8][9].
  • Seizures: Any new or unusual shaking, staring spells, or loss of muscle control [10][1].
  • Extreme Weakness: A sudden “floppiness” or loss of muscle tone (hypotonia) [8].
  • Inability to Retain Fluids: Persistent vomiting where emergency calories cannot be kept down [5][11].

Urgent Warning Signs (Contact Your Metabolic Team Immediately)

If these occur, you should immediately start your personalized “sick-day plan” and call your metabolic specialist right away:

  • Persistent Vomiting: Your child cannot keep down fluids or their specialized formula [5][11].
  • Refusing to Eat: Poor feeding or a complete lack of appetite during an illness [8][9].
  • Signs of Dehydration: Fewer wet diapers, no tears when crying, or a dry mouth [11][7].

Your Sick-Day Plan: The First Line of Defense

A sick-day plan is a set of written instructions from your metabolic team designed to stop catabolism before a crisis becomes severe. You must follow your clinician-completed emergency plan rather than improvising generic recipes [12][13]:

  1. High-Carbohydrate Fluids: You will likely be told to give your child an exact prescribed volume and concentration of an “emergency feed” to provide easy energy [14][15].
  2. Protein Hold: Your doctor may instruct you to temporarily stop or reduce “natural” protein. Never withhold protein for longer than your doctor explicitly recommends, as the body eventually needs those building blocks [13][16].
  3. L-Carnitine: Your child may need an adjusted dose of L-carnitine if prescribed [17][18].

What Happens in the Hospital

If your child cannot keep fluids down or their symptoms are progressing, they will need hospital stabilization. Emergency treatment is specialized and directed by the metabolic or critical care team using your Emergency Letter [12][19]:

  • IV Therapy: Providing IV dextrose (sugar) and specific fluids to stop catabolism, at rates calculated by the medical team [20][12].
  • Biochemical Monitoring: The ER team will run blood tests to check:
    • Blood Gases/pH: To see if the blood has become too acidic (metabolic acidosis) [21][22].
    • Ammonia: To check for hyperammonemia, a toxic buildup of waste [23][24].
    • Electrolytes and Glucose: To monitor for imbalances [21][19].

In very rare and severe cases where therapies fail or uncontrollable hyperammonemia/acidosis occurs, a process called dialysis may be considered to manually filter the blood [25][9].

Common questions in this guide

What can trigger a metabolic crisis in a child with MCEE deficiency?
Infection, fever, fasting, and other physical stress can trigger a metabolic crisis. During stress, the body may break down its own fat and muscle, causing metabolites to build up faster than they can be cleared. This is why an individualized sick-day plan should be started early when illness begins.
Which symptoms mean I should call 911 for MCEE deficiency?
Call 911 or go to the emergency room if your child is very difficult to wake, confused, having trouble breathing, having a seizure, suddenly floppy, or unable to keep fluids down. Do not force oral fluids if your child is extremely drowsy, having a seizure, or cannot swallow safely. Bring the Emergency Letter and do not wait for laboratory results.
When should I start my child’s sick-day plan?
Start the plan at the first illness signs covered by your metabolic team’s instructions, such as vomiting, poor feeding, or refusing food, and contact the team immediately. Use the exact emergency feed and instructions prescribed for your child rather than a generic recipe. Seek emergency care if fluids cannot be kept down or symptoms are worsening.
What does a sick-day plan for MCEE deficiency usually include?
The plan may specify high-carbohydrate emergency fluids, a temporary reduction or hold of natural protein, and an adjusted L-carnitine dose if prescribed. Protein should never be withheld longer than the clinician directs. The exact amount, concentration, and timing must come from your child’s metabolic team.
What happens when a child with MCEE deficiency is treated in the hospital?
The hospital team may give intravenous dextrose and other fluids to provide energy and stop the body from breaking down its own tissues. Blood tests may check blood acidity, ammonia, electrolytes, and glucose. In rare, severe cases, dialysis may be considered if ammonia or acidosis cannot be controlled.
Why should I bring an Emergency Letter to the emergency room?
The Emergency Letter gives the emergency team the child’s specific diagnosis, MCEE subtype, and important instructions for managing a metabolic crisis. It can help clinicians begin appropriate treatment quickly, especially when the child is too unwell to provide medical details.

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References

References (25)
  1. 1

    Methylmalonyl Coenzyme A (CoA) Epimerase Deficiency, an Ultra-Rare Cause of Isolated Methylmalonic Aciduria With Predominant Neurological Features.

    Diogo R, Rua IB, Ferreira S, et al.

    Cureus 2023; (15(10)):e48017 doi:10.7759/cureus.48017.

    PMID: 38034150
  2. 2

    Methylmalonyl-CoA Epimerase Deficiency Mimicking Propionic Aciduria.

    Abily-Donval L, Torre S, Samson A, et al.

    International journal of molecular sciences 2017; (18(11)) doi:10.3390/ijms18112294.

    PMID: 29104221
  3. 3

    Postpyloric nutrition to prevent emergencies - a step away from repeat inpatient care in children with methylmalonic acidaemia and propionic acidaemia - a case report of four cases.

    Schumann S, Rommel FR, Cantez S, et al.

    Frontiers in pediatrics 2023; (11()):1078425 doi:10.3389/fped.2023.1078425.

    PMID: 36814590
  4. 4

    Decrease of disease-related metabolites upon fasting in a hemizygous knock-in mouse model (Mut-ko/ki) of methylmalonic aciduria.

    Lucienne M, Mathis D, Perkins N, et al.

    JIMD reports 2021; (58(1)):44-51 doi:10.1002/jmd2.12182.

    PMID: 33728246
  5. 5

    The phenotypic spectrum of organic acidurias and urea cycle disorders. Part 1: the initial presentation.

    Kölker S, Garcia-Cazorla A, Cazorla AG, et al.

    Journal of inherited metabolic disease 2015; (38(6)):1041-57 doi:10.1007/s10545-015-9839-3.

    PMID: 25875215
  6. 6

    Development of a signs and symptoms outcome measure for caregivers of patients with methylmalonic acidemia and propionic acidemia (MMAPAQ).

    Sikirica V, Schwartz EJ, Vockley J, et al.

    Molecular genetics and metabolism 2024; (143(1-2)):108577 doi:10.1016/j.ymgme.2024.108577.

    PMID: 39303317
  7. 7

    Methylmalonyl-coA epimerase deficiency: A new case, with an acute metabolic presentation and an intronic splicing mutation in the MCEE gene.

    Waters PJ, Thuriot F, Clarke JT, et al.

    Molecular genetics and metabolism reports 2016; (9()):19-24 doi:10.1016/j.ymgmr.2016.09.001.

    PMID: 27699154
  8. 8

    In-depth phenotyping reveals common and novel disease symptoms in a hemizygous knock-in mouse model (Mut-ko/ki) of mut-type methylmalonic aciduria.

    Lucienne M, Aguilar-Pimentel JA, Amarie OV, et al.

    Biochimica et biophysica acta. Molecular basis of disease 2020; (1866(3)):165622 doi:10.1016/j.bbadis.2019.165622.

    PMID: 31770620
  9. 9

    [N-carbamylglutamate in the treatment of neonatal organic acidemia crisis: a report of five cases].

    Zhao HY, Liang H, Li GY, et al.

    Zhongguo dang dai er ke za zhi = Chinese journal of contemporary pediatrics 2026; (28(5)):607-613 doi:10.7499/j.issn.1008-8830.2512091.

    PMID: 42130361
  10. 10

    Metabolic decompensation events among patients with propionic acidemia across the US: A large electronic medical record data study.

    Sikirica V, Banerjee G, Perera S, et al.

    Molecular genetics and metabolism 2025; (145(2)):109111 doi:10.1016/j.ymgme.2025.109111.

    PMID: 40311502
  11. 11

    Emergency management of critically ill adult patients with inherited metabolic disorders.

    Sulaiman RA, Alali A, Hosaini S, et al.

    The American journal of emergency medicine 2022; (55()):138-142 doi:10.1016/j.ajem.2022.02.053.

    PMID: 35313229
  12. 12

    Methylmalonic Acidemia.

    Mahmud S, Awais Ul Hassan Shah S, Ali S

    Journal of the College of Physicians and Surgeons--Pakistan : JCPSP 2015; (25(6)):462-4 doi:06.2015/JCPSP.462464.

    PMID: 26101005
  13. 13

    N-Carbamylglutamate Is an Effective Treatment for Acute Neonatal Hyperammonaemia in a Patient with Methylmalonic Aciduria.

    Yap S, Leong HY, Abdul Aziz F, et al.

    Neonatology 2016; (109(4)):303-7 doi:10.1159/000443630.

    PMID: 26907495
  14. 14

    General Anesthesia for a Child With Methylmalonic Acidemia Undergoing Oral Care and Dental Treatment Before Kidney Transplantation.

    Hano K, Kato M, Miyajima R, et al.

    Anesthesia progress 2024; (71(1)):39-41 doi:10.2344/anpr-70-03-10.

    PMID: 39503120
  15. 15

    Isolated methylmalonic acidemia with unusual presentation mimicking diabetic ketoacidosis.

    Dejkhamron P, Wejapikul K, Unachak K, et al.

    Journal of pediatric endocrinology & metabolism : JPEM 2016; (29(3)):373-8.

    PMID: 26581066
  16. 16

    Nutritional Management and Biochemical Outcomes during the Immediate Phase after Liver Transplant for Methylmalonic Acidemia.

    Siegel C, Arnon R, Florman S, et al.

    Nutrients 2020; (12(10)) doi:10.3390/nu12102976.

    PMID: 33003354
  17. 17

    Evaluation of long-term effectiveness of the use of carglumic acid in patients with propionic acidemia (PA) or methylmalonic acidemia (MMA): study protocol for a randomized controlled trial.

    Nashabat M, Obaid A, Al Mutairi F, et al.

    BMC pediatrics 2019; (19(1)):195 doi:10.1186/s12887-019-1571-y.

    PMID: 31196016
  18. 18

    Genetic testing is necessary for correct diagnosis and treatment in patients with isolated methylmalonic aciduria: a case report.

    Brennerová K, Škopková M, Ostrožlíková M, et al.

    BMC pediatrics 2021; (21(1)):578 doi:10.1186/s12887-021-03067-3.

    PMID: 34915869
  19. 19

    Continuous renal replacement therapy in a neonate with methylmalonic acidemia and severe hyperammonemia: A case report.

    Lin B, Huang Y, Yu Y, et al.

    Medicine 2025; (104(30)):e42046 doi:10.1097/MD.0000000000042046.

    PMID: 40725920
  20. 20

    Dietary Treatment from Birth to Pregnancy in a Woman with Methylmalonic Aciduria.

    Kowalik A, MacDonald A, Sykut-Cegielska J

    Medicina (Kaunas, Lithuania) 2021; (57(2)) doi:10.3390/medicina57020128.

    PMID: 33540566
  21. 21

    Acute fatal ventricular arrhythmia induced by severe hyperkalemia in a toddler with decompensated methylmalonic acidemia.

    Hakimzadeh Z, Gilani A, Yousefichaijan P, Sarmadian R

    Journal of medical case reports 2024; (18(1)):73 doi:10.1186/s13256-024-04406-5.

    PMID: 38395924
  22. 22

    Real-World Experience of Carglumic Acid for Methylmalonic and Propionic Acidurias: An Interim Analysis of the Multicentre Observational PROTECT Study.

    Yap S, Lamireau D, Feillet F, et al.

    Drugs in R&D 2024; (24(1)):69-80 doi:10.1007/s40268-023-00449-z.

    PMID: 38198106
  23. 23

    Liver transplantation in propionic and methylmalonic acidemia: A single center study with literature review.

    Pillai NR, Stroup BM, Poliner A, et al.

    Molecular genetics and metabolism 2019; (128(4)):431-443 doi:10.1016/j.ymgme.2019.11.001.

    PMID: 31757659
  24. 24

    Interorgan amino acid interchange in propionic acidemia: the missing key to understanding its physiopathology.

    Stanescu S, Belanger-Quintana A, Fernandez-Felix BM, et al.

    Amino acids 2022; (54(5)):777-786 doi:10.1007/s00726-022-03128-6.

    PMID: 35098378
  25. 25

    Clinical Practice Recommendations on Kidney Management in Methylmalonic Acidemia: an Expert Consensus Statement From ERKNet and MetabERN.

    Servais A, Zacchia M, Dehoux L, et al.

    Kidney international reports 2024; (9(12)):3362-3374 doi:10.1016/j.ekir.2024.09.002.

    PMID: 39698355

This page is for informational purposes only and does not constitute medical advice. It explains emergency warning signs and sick-day planning for a child with MCEE deficiency; follow your child’s individualized plan and contact the metabolic team or emergency services for urgent concerns.

Guide contents Methylmalonic acidemia due to methylmalonyl-CoA epimerase deficiency
Research & Literature
02 Confirming the Diagnosis 04 Daily Management and Treatment