Hot Seat #139: 6 wk M with failure to thrive
Posted on: October 15, 2019, by : Michael Hrdy
Michael Hrdy, MD with Sam Zhao, MD. Children’s National Medical Center
HPI: A 6 week old full-term male presents to the ED as a referral from the primary care doctor due to failure to thrive, lethargy, and abnormal newborn screen. Mom was initially called to bring the baby to the primary care physician due to abnormal newborn screening labs. The PMD then referred the patient in to the ER when the patient was found to be lethargic on exam, in the setting of abnormal thyroid function studies. However, the mother felt the infant was at his baseline mentation without any recent changes. Mom is able to give an excellent feeding history of 90ml hydrolyzed formula every three hours, mixed correctly. He is making 5-8 wet diapers per day and 1-2 soft brown stools per day.
ROS: No fevers. No vomiting, diarrhea or bloody stool. No shortness of breath. No nasal congestion or cough. No change in amount of time spent awake or asleep.
PMHx: Born FT due to mother with gestational diabetes. Hypoglycemic requiring IV glucose in the NICU until enteral feeding started. Sepsis evaluation was negative. Due to concern for milk protein allergy, the patient was discharged on hydrolyzed formula. Birth weight 6.2 lbs.
FHx: No history of thyroid disease
Social: Several other children at home, all healthy
Physical Exam:
T 36.8, HR 124, RR 38, BP 75/52, 100% on RA, Wt 9.0 lbs
General: Alert. appropriate for age.
Skin: Warm. dry. intact. no rash. not jaundiced.
Head: Normocephalic. atraumatic. anterior fontanelle soft and flat. Posterior fontanelle open and flat
Neck: Supple. trachea midline. No lymphadenopathy.
Eyes: Pupils are equal, round and reactive to light. Extraocular movements are intact. Normal conjunctiva without discharge or jaundice.
Ears, nose, mouth and throat: Oral mucosa moist. No pharyngeal erythema or exudate. Congested nares. No macroglossia
Cardiovascular: Regular rate and rhythm. No murmur. Normal peripheral perfusion. Extremity pulses equal. 2+ femoral pulses
Respiratory: Lungs are clear to auscultation. Respirations are non-labored. Breath sounds are equal. Symmetrical chest wall expansion.
Chest wall: No tenderness. No deformity.
Back: Normal range of motion
MSK: Normal ROM. moves all extremities.
GI: Soft. Non distended. Normal bowel sounds.
GU: Normal genitalia for age
Neurological: No focal neurological deficit observed. Appropriate tone.
The patient is reweighed and remains 9 lbs.
After multiple attempts, BMP, TSH, and free T4 were obtained but no IV could be placed.
Point of care glucose returned 51 mg/dL.
Upon re-evaluation, the patient’s exam is unchanged. Mom is not updated as she was asleep in the room.
The nurse is asked to have Mom feed the baby his formula while you go see a potentially unstable patient who just arrived.
The remaining labs result. BMP: 138/5.2/104/22/14/0.34 Glucose 60 mg/dL. TSH 5.0 nIU/mL (Normal 0.59-6.78). Free T4 0.54 ng/dL (Normal 0.93-1.45).
While you are in the room with the other patient, another physician notes the glucose value and has the nurse give a 10cc/kg D10W bolus and a 20cc/kg NS bolus. The blood sugar responds to 141.
While the nurse is performing these tasks she becomes concerned that Mom is still very sleepy and is difficult to arouse. Another provider raises the concern for drug abuse.
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What an interesting case! There are two things that stand out to me:
– Is the drowsiness in the mother related to the hypoglycemia and low free T4 level in the patient? Since the baby is bottle fed, likely not – unless there’s a component of neglect/abuse in this patient. If the patient were breastfed, then this may play a greater role in the clinical management. A quick search revealed a few studies that suggest opioid use as an etiology of hypoglycemia, so if that crosses into the milk supply, it could hypothetically cause hypoglycemia in the infant as well. That doesn’t seem to be the issue with our patient.
– Does the patient need floor or ICU level care? Technically, our patient was on the cusp of being hypoglycemic (a common cut-off we use in neonates, though I can’t find any specific literature to support it, is 50 mg/dL). Our patient remained happy, alert, and interactive despite the low BG of 51 mg/dL. I would argue that, if it’s not too busy in the ED, the patient would benefit from close observation and admission to the floor if he remained stable for four hours. But, given you had already been called away for a more sick patient, there is certainly the possibility that this child will get acutely sick and there may not be a nurse or a physician at the bedside to notice. On a busy day, it may be worthwhile to advocate for an ICU admission for frequent glucose monitoring and initiation of definitive therapy.
A couple random thoughts to consider:
1. Is the mother appropriately tired/sleepy because she is chronically sleep-deprived from having a 6-week-old infant and “several other children at home.” Why do we ER docs always jump to the most sinister concern — abuse/neglect?!?
2. This baby is THRIVING!!! If I did my math correct, this baby has gained 46 ounces (from 6#2oz at birth to 9# at 6 weeks) in 42 days. Given the lowish glucose in the ED together with the h/o hypoglycemia in the NICU, I think we need to give the diagnosis of (congenital) hyperinsulinism a quick 2nd look. Remember, in babies, insulin acts as an anabolic growth hormone. I presume that the neonatal hypoglycemia was attributed to h/o maternal diabetes, but it’s interesting that this infant was not macrosomic at birth — just the opposite, kind of small at 6#2oz. I agree with Sam that a BS of 51 is not truly low for an infant (most use 50, others use 47 as cutoffs), but the history surrounding this patient may be concerning. I’d seek clarification as to when the last time the child fed was in relation the BS of 51. If it was <2 hours before, I'd be quite concerned for primary hyperinsulinism. To make this diagnosis, I'd consult Endocrinology, but my understanding is that one would need to show an elevated insulin level while patient was hypoglycemic.