Endocrinology Pt. 2 Flashcards
What HLA haplotype is seen in 95% of patients with type 1 DM?
DR3 or DR4
What are some environmental triggers for DM type 1?
Viral infections (enteroviruses and rubella)
Early introduction of cow’s milk (controversial)
What autoimmune factors contribute to DM type 1?
- Islet cell antibodies (ICA) are present in 85% of patients
- ICA may be detected in asymptomatic patients 10 years before onset of clinical symptoms
- Other immunologic markers
- Antibodies against insulin and against glutamic acid decarboxylase
What is required for a child to develop type 1 DM?
A combination of ICA, environmental factors, and a genetic predisposition
The classic presentation of DM type 1 includes several weeks of…(3)
Polyuria
Polydipsia
Nocturia
In what percentage of patients is Diabetic ketoacidosis the initial presentation of DM type 1?
25%
Girls who have protracted cases of _____ _________ may have early type 1 DM
monilial vulvovaginitis
What is required to diagnose patients with type 1 DM?
Patients must have hyperglycemia documented by a random blood sugar above 200 mg/dL with polyuria, polydipsia, weight loss, or nocturia
What types of insulin are used to treat DM type 1?
Short-acting
Intermediate-acting
Long-acting
Very long-acting
What is the honeymoon period of DM type 1?
Within a few weeks after initial diagnosis, 75% of patients exhibit a temporary progressive reduction in their daily insulin requirements; this is because of transient recovery of residual islet cell function resulting in endogenous release of insulin in response to carbohydrate exposure
What is the Somogyi phenomenon in DM type 1?
This occurs when the evening dose of insulin is too high causing hypoglycemia in early morning hours, resulting in the release of counter-regulatory hormones (epinephrine/glucagon) to counteract the insulin-induced hypoglycemia; patient then has high blood glucose and ketones in the morning
How do you prevent the Somogyi phenomenon (hyperglycemia in the morning?)
The treatment is to lower the bedtime insulin dose
What are some long term complications of DM type 1?
- Microvascular complications: diabetic retinopathy, nephropathy, neuropathy
- Macrovascular complications (usually seen in adults): atherosclerosis, HTN, heart disease, stroke
- DKA: when ill or noncompliant
Type 2 DM occurs in _-_% of all children with diabetes
2-3%
Which type of diabetes has the strongest hereditary component?
Type 2
What is likely the cause of DM type 2?
Combination of peripheral tissue resistance to insulin and progressive decline in insulin secretion
What is the clinical presentation of DM type 2?
- Obesity
- Acanthosis nigricans
- Asymptomatic to mild DKA
What is the management of DM type 2?
Oral hypoglycemic agents if blood sugar levels are not very high
Insulin therapy may be required
What is the definition of DKA?
Hyperglycemia uually greater than 300 mg/dL with ketonuria and a serum bicarbonate level < 15 mmol/L or a serum pH < 7.3
What are the roles of counter regulatory stress hormones in DM type 2?
Hyperglycemia resulting from insulin deficiency leads to an osmotic diuresis with polyuria and eventual dehydration; counter regulatory stress hormones (glucagon, epinephrine, cortisol, GH) are released and contribute to fat breakdown (lipolysis)
Glucagon stimulates conversion of FFA to ketones and eventually leads to DKA
How does mild DKA present? How does severe DKA present?
Mild: vomiting, polyuria, polydipsia, and mild to moderate dehydration
Severe: severe dehydration, abdominal pain (mimics appendicitis) and rapid and deep (Kussmaul) respirations, and coma
What are the lab findings in type 2 DM?
- Anion gap metabolic acidosis
- Hyperglycemia and glucosuria
- Ketonemia and ketonuria
- Hyperkalemia caused by metabolic acidosis
What are the steps in management of DM type 2?
- Fluid and electrolyte therapy
- Gradual decline in osmolality (minimizes risk of cerebral edema)
- Potassium repletion (potassium acetate and potassium phosphate)
- Regular insulin
- Combination of IVF and insulin should revrese ketogenesis
Why is potassium repletion important in DM type 2?
Important because all patients are potassium depleted, even with a normal serum potassium
Potassium phosphate helps increase levels of 2,3-DPG which in turn shifts the oxygen dissociation curve to tohe right and makes oxygen more readily available to the tissues
What serious complication of DM type 2 usually occurs 6-12 hours into therapy and has a mortality rate of 70%?
Cerebral edema
What factors regulate the hypothalamic pituitary thyroid axis?
Thyroxine (T4), triiodothyronine (T3), TRH, TSH
What is bound to T4 and T3 in circulation
Thyroid binding proteins, including thyroid-binding globulin (TBG) and thyroid binding prealbumin (TBPA)
When are T4 and T3 in their biologically active forms?
When they are unbound
What is the clinical presentation of hypothyroidism?
- Suboptimal growth velocity with delayed bone age
- Goiter
- Myxedema (puffy skin)
- Amenorrhea or oligomenorrhea in adolescent girls
What is the most common metabolic disorder?
Congenital hypothyroidism
What is the most common cause of congenital hypothyroidism (90%)?
Thyroid dysgenesis: absent thyroid gland, thyroid hypoplasia, or ectopic thyroid gland
What is thyroid dyshormonogenesis?
What is the most common of these defects?
Multiple inborn errors of thyroid hormone synthesis
Pendred syndrome (organification defect) is most common - associated with sensorineural hearing loss
What maternal factors may lead to transient congenital hypothyroidism?
Use of PTU during pregnancy for maternal Graves’ disease may result in transient hypothyroidism (PTU crosses placenta)
Maternal autoimmune thyroid disease - maternal thyroid blocking antibodies may cross the placenta and block TSH receptors on the newborn thyroid gland
How do most newborns with hypothyroidism present?
Asymptomatic and unremarkable physical examination (T4 is not essential for fetal growth)
Thyroid hormone is essential for normal brain growth during the first __ years of life
2 years