II. Case Presentation
The index patient was a 5-month-old male infant, born to non-consanguineous healthy parents. He was the second child of the family and his female sibling was healthy. No history of abortion, early death, or prenatal abnormality was reported. )Figure.1 )
The baby was born post-term (at 40 weeks of gestation) through vaginal delivery with a birth weight of 3500 grams. At birth, the cleft lip and palate were diagnosed, and he was admitted to the neonatal ward for 24 hours to practice sucking under health care team observation. The physical examination was otherwise normal. He was PO tolerant and was discharged on the second day of birth with personal permission.
He was screened for the presence of accompanying anomalies by the ultrasound of the brain, heart, abdomen, and pelvis, which revealed normal results except for patent foramen ovale (PFO) and a small patent ductus arteriosus (PDA). (Figure.2 (A-C) )
The mother states that the number of diapers that became completely heavy from birth was about 7-8 diapers per day. The infant had no problem thereafter and had a normal weight gain. At the fourth month of age, the mother noticed episodes of myoclonic (UWG) movements lasting for a few seconds about 2 to 3 times during daytime and when falling asleep. The frequency of these attacks gradually increased, and limbs spasm was added on. During an outpatient visit to a pediatric neurologist, the primidone (Liskantin®) is started, and he was recommended to return if there was no response to treatment. The levetiracetam was added after a week due to the continued seizure attacks, with no significant response, and the infant was admitted to the Qom Shohada Hospital. In the spiral brain computed tomography (CT) the septal agenesia was suspected and in the magnetic resonance imaging (MRI), the septum pellucidum was absent and holoprosencephaly was reported. The electroencephalogram (EEG) was abnormal. In addition, the serum sodium level was above the normal range (Na: 169 meq/L). During his two-week admission, the number of seizure episodes declined but the hypernatremia did not resolve.
Due to his refractory hypernatremia, he was referred to the Mofid Children’s Hospital and the nephrology and neurology services were consulted. Upon admission to this center, he had fever and hypernatremia (Na: 170 meq/L). The maintenance serum (1.2 L) was placed for the patient and the paraclinical workup was performed to rule out infectious etiologies (including COVID-19 PCR), all of which were negative. On the second day of hospitalization, according to the low urine specific gravity (SG: 1003) and high serum sodium level (Na: 169 meq/L), he was diagnosed with diabetes insipidus (DI). With the serum sodium of 145 meq/L, he received a puff of DDAVP spray equivalent to 10 micrograms of desmopressin, while on cardiac monitoring and vital signs check. The serum sodium reached 131 meq/L two hours after receiving desmopressin and 118 meq/L four hours later, and the urine SG reached 1011. The patient developed seizures, controlled by hypertonic sodium and diazepam. Three days later, the patient’s condition stabilized and he was re-initiated on desmopressin spray, diluted in a proportion of 1:4. There was no change in plasma sodium and urine SG levels. The next day, with a serum sodium level of 144 meq/L, a two-fold dose of desmopressin (1:2 concentration) was administered which resulted in a sodium drop to 134 meq/L, 2 hours later, and 119 meq/L, 4 hours later, with urine SG of 1015. and received hypertonic sodium again. In the re-administration of a quarter dose with serum sodium of 154 meq/L, this time, he experienced a decrease in sodium by 102, 2 hours after receiving desmopressin, the urine SG reached 1015, and urine volume decreased subsequently. The desmopressin was discontinued and no hypernatremia was detected during the follow-up.