Paediatric renal and musculoskeletal

This chapter pairs kidney patterns in children with the orthopedic devices that show up beside them on the exam: casts, harnesses, and the climb-up-the-legs sign that means muscle disease.

Nephrotic syndrome vs acute glomerulonephritis

Both make a child look “puffy,” so the stem that only says edema is not enough. Name the urine and the blood pressure. Nephrotic disease is a leaky glomerular filter that dumps protein; post-strep AGN is an inflamed filter that bleeds and holds salt and water. Wrong map → wrong first priority.

In nephrotic syndrome; often idiopathic minimal-change disease in preschool and early school-age kids; the glomerulus loses large amounts of protein into the urine. Serum albumin falls, oncotic pressure drops, and fluid shifts into the tissues. That is why the child looks swollen (often starting around the eyes in the morning) and why the urine foams: protein lowers surface tension. Lost immunoglobulins raise infection risk; lost antithrombin and other clotting proteins raise thrombosis risk. Skin under taut edema breaks down easily, so turn, dry, and protect pressure points while you track daily weight and abdominal girth as fluid markers.

Treatment pathways commonly use corticosteroids as ordered for steroid-responsive disease, plus salt/fluid guidance from the plan. The distractor that looks kind is unrestricted visitors and busy playrooms while albumin and immune proteins are still low, or chasing BP meds as the first thought when the stem is frothy urine and marked edema without hypertensive crisis cues.

Acute post-streptococcal glomerulonephritis is different physics. Days to a few weeks after group A strep pharyngitis or skin infection, immune complexes injure the glomerulus. RBCs and casts darken the urine to tea or cola color; GFR falls so urine output drops; salt and water retention push blood pressure up. Mild edema can still appear, but hypertension and fluid overload; including pulmonary crackles or headache/visual change that hint at hypertensive encephalopathy; are the exam priorities. Monitor BP, fluid balance, and neurologic status; follow the ordered fluid and sodium limits.

The classic distractor is treating every puffy child as nephrotic (steroids first, infection focus only) when the urine is cola-colored after a documented strep illness and the BP is high. Another miss: reassuring parents that dark urine after strep is “just dehydration” without checking pressure and output. Match tea urine + oliguria + hypertension to AGN; match frothy massive protein + marked edema to nephrotic.

Urinary structure and infection

Infants do not point to dysuria. A febrile, irritable, poorly feeding baby with foul-smelling urine is a UTI until the workup says otherwise; not “teething” or a viral shrug. Structure problems (hypospadias, reflux pathways) change what you teach and when you cut foreskin. Get the specimen right, then teach prevention that parents can actually do.

• Infants cannot localize dysuria; fever and irritability matter.
• Teach front-to-back wiping, unfinished antibiotic courses, and hydration.
• Hypospadias: surgical repair uses foreskin tissue; hold routine circumcision until the plan is set.

Why fever and fussiness count: the immature child mounts a systemic picture before a clear “it burns when I pee” story. Dirty-catch bags contaminate easily; follow the facility pathway for clean-catch, catheter, or suprapubic sample when culture will drive antibiotics. Start teaching while you wait for results: wipe front to back in girls, avoid harsh bubble baths that irritate the urethra, finish the full antibiotic course even when symptoms fade, and keep fluids up so the bladder flushes.

Hypospadias places the urethral meatus on the ventral penis rather than at the tip. Repair often uses foreskin tissue as a graft or flap. Routine newborn circumcision removes that tissue before the surgeon has planned reconstruction; so hold circumcision until urology sets the repair sequence. The distractor that looks routine is “circumcise now for hygiene, fix the urethra later.” Another miss: treating a bag specimen as definitive culture when contamination is obvious and clinical suspicion is high.

Hemolytic uremic syndrome is a microangiopathic hit to red cells, platelets, and kidneys, classically after a diarrheal illness (often Shiga-toxin E. coli). Bloody diarrhea, then pallor, bruising, oliguria, and rising creatinine. Supportive care and dialysis if the kidneys shut down. Do not give antimotility drugs that keep toxin in the gut, and do not start antibiotics for that diarrhea on a whim when the stem is HUS. This is not “gastroenteritis, push Pedialyte and loperamide.”

Vesicoureteral reflux lets urine wash back toward the kidney, so UTIs repeat and scars form. Teaching is finishing antibiotics, hygiene, timed voiding, and prophylactic antibiotics or surgical correction as the urology plan says. Enuresis after the age when dryness is expected is not laziness. Rule out UTI and constipation, skip punishment, use alarms and ordered desmopressin teaching (night fluid limits as instructed).

Casts and congenital orthopedic disorders

Orthopedic stems in pediatrics are mostly device and perfusion checks. A cast that looks neat can still kill distal tissue. A Pavlik harness only works if it stays on the hours ordered. A boy who walks his hands up his thighs to stand is giving you a neuromuscular clue, not a quirky habit.

1. Check fingers/toes: color, warmth, capillary refill, movement, sensation.
2. Pain out of proportion or pain with passive stretch: escalate for compartment risk.
3. Keep cast clean/dry; never insert hangers or powder deep inside.
4. Elevate the limb as ordered to limit swelling.

After casting or with any circumferential dressing, compare the casted digits to the opposite side: pink and warm beats pale, dusky, or cool; brisk refill beats delayed; can wiggle and feel beats numbness or paralysis. Unrelieved pain, especially pain with passive stretch of the fingers or toes, is the classic compartment-syndrome cue; pressure inside the fascia is cutting off muscle and nerve blood flow. Elevate as ordered to limit dependent swelling; keep plaster dry; never stick hangers, rulers, or powder deep inside to scratch; that abrades skin and invites infection under a closed cast.

The distractor that looks patient is “call the clinic in the morning” for cool, numb toes, or giving another dose of analgesic and walking away when pain is out of proportion. Loosen restrictive outer wraps per protocol and notify now. Comfort measures do not replace a neurovascular emergency.

Developmental dysplasia of the hip (DDH) is unstable or shallow hip seating. Exam cues include uneven gluteal folds, limited abduction, and Ortolani/Barlow maneuvers in the age window where they are used. The Pavlik harness holds the hips flexed and abducted so the femoral head stays seated in the acetabulum while it deepens. Parents must leave straps and angles as the clinician set them; DIY tightening or removing “just for a bath every time” undoes reduction. Check skin under straps for breakdown; sponge-bathe as taught when the harness stays on.

Clubfoot (talipes equinovarus) is treated with serial casting and bracing; missed appointments let the foot relapse into the deformed position. A scoliosis brace only slows or controls curve progression when worn the hours ordered; “wear it to school photos” is not the plan. Duchenne muscular dystrophy, typically in young boys, weakens proximal muscles; Gower sign is using the hands to walk up the thighs when rising from the floor because hip girdle power is not enough. That finding needs evaluation, not a sports-readiness shrug.

Juvenile idiopathic arthritis is immune joint inflammation in a child: morning stiffness, swollen joints, and uveitis that can steal vision without much pain, so slit-lamp exams as ordered are not optional. NSAIDs, disease-modifying drugs, and warm baths for stiffness as taught. Legg-Calvé-Perthes is avascular necrosis of the femoral head in a school-age child with a limp; rest and containment of the head in the acetabulum as the orthopedic plan says, not “run it off.” Osteomyelitis is bone infection: fever, point tenderness, refusal to bear weight. Blood cultures as timed, long IV antibiotics, immobilize. Do not apply heat and send them to gym.

Distractors that fail these items: adjusting Pavlik abduction “so the baby looks more comfortable,” circumcising a hypospadias infant before repair planning (covered above), or dismissing Gower as laziness. Device adherence and distal perfusion beat cosmetic convenience.

Priority map